Liquid crystal display apparatus, driving method for same, and driving circuit for same

ABSTRACT

The liquid crystal display apparatus is provided with a display unit, a video signal driving circuit, a scanning signal driving circuit, a common electrode potential controlling circuit, and a synchronizing circuit. The display unit has a scanning electrode, a video signal electrode, a plurality of pixel electrodes arranged in matrix form, a plurality of switching elements which transmit video signals to the pixel electrodes, and a common electrode. After the scanning signal driving circuit scans the entire scanning electrodes and transmits video signals to the pixel electrodes, the common electrode potential controlling circuit changes the potential of the common electrode into a pulse shape, overdrives video signals, or increases a torque required to return to a state in which no voltage is applied.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/300,483, filed Dec. 15, 2005, which claims priority to JapanesePatent Application No. 2004-363407, filed Dec. 15, 2004, the contents ofall of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to a liquid crystal display apparatus, adriving method for the same, and a driving circuit for the same. Moreparticularly, the present invention relates to a high-efficiency liquidcrystal display apparatus capable of responding at high speed, a drivingmethod for the same, and a driving circuit for the same.

2. Description of the Related Art

With advancements in the multimedia age, a liquid crystal displayapparatus from small-sized ones used in projectors, cellular telephones,view finders, and so on to large-sized ones used in notebook PCs,monitors, televisions, and so on has rapidly come into widespread use.Moreover, to electronic equipment such as viewers and PDAs and furtherto amusement machines such as handheld video game machines and pinballmachines as well, middle-sized liquid crystal display apparatuses havebecome indispensable. On the other hand, liquid crystal displayapparatuses have been used in all sorts of units including householdappliances such as refrigerators and microwave ovens. At present, inmost liquid crystal display elements, a twisted nematic (TN) displaysystem is used. The liquid crystal display elements having the TN typedisplay system are made of a nematic liquid crystal composition. Whenthe conventional TN type liquid crystal display elements are subjectedto simple matrix driving, it has been found that their display qualityis not high and their number of scanning lines is limited. Therefore, inthe simple matrix driving, an STN (Super Twisted Nematic) type liquidcrystal display system is mainly used instead of the TN type liquidcrystal display system. The STN type liquid crystal display system hasimproved contrast and viewing angle dependence when compared withinitial simple matrix driving system using the TN type liquid crystaldisplay system. However, since the STN type liquid crystal displayapparatuses are low in response speed, these are not suitable for movingimage displays. To improve the display performance of the simple matrixdriving system, an active matrix system, in which each pixel is providedwith a switching element, has been developed and widely used. Forexample, the TN type display apparatuses having thin film transistors(TFTs), that is, TN-TFT type display apparatuses are widely used. Sincethe active matrix system using the TFTs has a higher display qualitythan the simple matrix driving system, the TN-TFT type liquid crystaldisplay apparatuses have become mainstream in the market at present.

On the other hand, due to a demand for even higher image quality, amethod for improving viewing angles has been studied, developed, andthen become commercially practical. As a result, the mainstream ofpresent high-performance liquid crystal displays are divided into threetypes, that is, TN-TFT type active matrix liquid crystal displayapparatuses using compensated films, TFT type active matrix liquidcrystal display apparatuses of an in-plane switching (IPS) mode, and TFTtype active matrix liquid crystal display apparatuses of a multi-domainvertical aligned (MVA) mode.

In these active matrix liquid crystal display apparatuses, an imagesignal having a frequency of 30 Hz is generally used and refreshed bythe frequency of 60 Hz for positive-negative writing. A time taken forone field is about 16.7 milliseconds (ms); that is, the total time takenfor the positive and negative fields is called one frame and is about33.3 ms. In contrast, with the response speed of present liquid crystaldisplay apparatuses, even their fastest response speed is onlyrepresented as such a frame time even with consideration given toresponses during their intermediate gradation display. Because of this,to display video signals of moving images, high-speed computer graphics(CG), and high-speed game images, it is necessary to secure a fasterresponse speed than that represented by the present frame time.

In addition, dominant pixel sizes are on the order of 100 ppi (pixelsper inch) at present and higher definition is achieved by the twomethods described below. One method is a method for decreasing pixelsizes through enhanced processing accuracy and the other is a method forfabricating a field-sequential (time-sharing) color liquid crystaldisplay apparatus in which a backlight serving as the illuminating lightof the liquid crystal display apparatus is switched in time sequenceamong red, green, and blue and at the same time, red, green, and blueimages are displayed. In the latter method, since there is no need tospatially dispose a color filter, it is possible to achieve definitionthree times as high as the conventional ones. In the field-sequentialliquid crystal display apparatus, there is a need to display one colorin a time corresponding to one-third of one field and hence, a timeusable to display the color is about 5 ms. Therefore, the liquid crystalitself is required to respond in less than 5 ms.

From the need for such a high-speed liquid crystal, various techniqueshave been studied and several high-speed display mode technologies havebeen developed. These high-speed liquid crystal technologies are broadlydivided into two trends. One of these is a technique for enhancing theresponse speed of the foregoing dominant nematic liquid crystals and theother is a technique for employing spontaneous polarization-type smecticliquid crystals capable of responding at high speed and so on. The firsttrend, that is, the enhancement of the response speed of the nematicliquid crystals is mainly effected by the following methods: (1) cellgaps are reduced to increase an electric field strength through theapplication of the same voltage; (2) a high voltage is applied toincrease the electric field strength and to promote a change in thestate of the liquid crystal (an overdrive system); (3) the viscosity ofthe liquid crystal is lowered; (4) a mode, which is considered to havehigh-speed responsivity in principle, is used, and so on.

Even in such high-speed nematic liquid crystals, the following problemsarise. In the high-speed nematic liquid crystal, since liquid crystalresponses are almost completed within its frame, a change in thecapacity of the liquid crystal layer remarkably increases due to theanisotropy of its dielectric constant. Due to the change in thecapacity, a holding voltage to be held by writing to the liquid crystallayer changes. Such a change in the holding voltage, that is, a changein an effective applied voltage makes the contrast lowered due toinsufficient writing. And when the same signal is written continuously,brightness continues to change until the change in the holding voltageceases and hence, several frames are required to obtain stablebrightness.

To prevent such responses requiring several frames, it is necessary toestablish a one-to-one correspondence between an applied signal voltageand an obtained transmittance. In active matrix driving, a transmittanceafter a liquid crystal response is determined by the amount of chargeaccumulated in a liquid crystal capacitor after the liquid crystalresponse instead of a signal voltage is applied. This is because activedriving is constant-charge driving in which a liquid crystal is made torespond by a held charge. The amount of a charge supplied from theactive element is determined by a charge accumulated before apredetermined signal is written and a write charge newly written whenits minute amount of leakage and so on are ignored. In addition, acharge accumulated after the liquid crystal responds also changesthrough the physical property constant of the liquid crystal and pixeldesign values such as an electrical parameter and a storage capacitor.Because of this, to establish the correspondence between the signalvoltage and the transmittance, the followings are necessary: (1)correspondence between the signal voltage and the write charge, (2) theaccumulated charge before the writing, and (3) acquiring information forcalculating the accumulated charge after the response and calculatingactually. As a result, it is necessary to provide a frame memory usedfor storing the item (2) across an entire screen and a calculating unitused for calculating the items (1) and (3).

On the other hand, as a method of establishing the one-to-onecorrespondence without the use of the foregoing frame memory andcalculating unit, a reset pulse method is often used in which a resetvoltage is applied to align liquid crystals into a predetermined statebefore data is newly written. As an example, a technique described inIDRC 1997 pp. L-66 to L-69 (hereinafter referred to as “secondpublication”) will be explained. In the second publication, an OCB(optically compensated birefringence or optically compensated bend) modeis used in which the alignment of the nematic liquid crystal is apie-type alignment and a compensated film is added. A response speed inthe liquid crystal mode is on the order of 2 to 5 milliseconds andtherefore significantly faster than that in conventional TN mode. As aresult, a response should essentially complete within one frame, whileas described above, since a significant decrease in a holding voltageoccurs due to a change in a dielectric constant resulting from theresponse of the liquid crystal, several frames are required until astable transmittance can be obtained. In view of this, a method foralways writing a black image after the writing of a white image withinone frame is shown in FIG. 5 of the second publication. This figure willbe quoted as FIG. 4. In FIG. 4, a horizontal axis represents time and avertical axis represents brightness. A dotted line represents a changein brightness during normal driving and a stable brightness is reachedat the third frame. According to the reset pulse method, since apredetermined state is always secured at the time of the writing of newdata, a one-to-one correspondence between a certain written signalvoltage and a certain transmittance can be observed. Through theone-to-one correspondence, driving signals are generated very easily anda unit such as a frame memory, which stores previously writteninformation, becomes unnecessary.

The configuration of a pixel of an active matrix liquid crystal displayapparatus will be summarized below. FIG. 1 is a circuit diagram of oneof the pixels of a conventional active matrix liquid crystal displayapparatus. As shown in FIG. 1, the pixel of the active matrix liquidcrystal display apparatus comprises a MOS transistor (Qn) (hereinafterreferred to as “transistor Qn”) 904, a storage capacitor 906, and aliquid crystal 908. The MOS transistor (Qn) 904 has a structure in whicha gate electrode is connected to a scanning line 901 (or a scanningsignal electrode), either a source electrode or a drain electrode isconnected to a signal line 902 (or a video signal electrode), and theremainder of these is connected to a pixel electrode 903. The storagecapacitor 906 is formed between the pixel electrode 903 and a storagecapacitance electrode 905. The liquid crystal 908 is sandwiched betweenthe pixel electrode 903 and an opposing electrode (or a commonelectrode) Vcom 907.

In notebook personal computers (notebook PCs) which form a largeapplication market for liquid crystal display apparatuses at present, anamorphous silicon thin film transistor (a-Si TFT) or a polycrystallinesilicon thin film transistor (p-Si TFT) is used as the transistor (Qn)904 and a TN liquid crystal is used as the liquid crystal material ingeneral. FIG. 2 is an equivalent circuit diagram of a TN liquid crystal.As shown in FIG. 2, the equivalent circuit of the TN liquid crystal canbe represented as a circuit in which the capacitive component C3 (itselectrostatic capacitance Cpix) of the liquid crystal is connected inparallel to a resistor R1 (its resistance Rr) and a capacitance C1 (itselectrostatic capacitance Cr). In this equivalent circuit, theresistance Rr and the capacitance Cr are components which determine theresponse time constant of the liquid crystal.

A timing chart of a scanning line voltage Vg, a signal line voltage (orvideo signal voltage) Vd, the voltage of the pixel electrode 903(hereinafter referred to as “pixel voltage”) Vpix, which are obtained bydriving such a TN liquid crystal by using the pixel circuit shown inFIG. 1, is shown in FIG. 3. As shown in FIG. 3, by raising the scanningline voltage Vg to a high level VgH during a horizontal scanning period,the n-type MOS transistor (Qn) 904 is turned on and then the signal linevoltage Vd, which is inputted into the signal line 902, is transferredto the pixel electrode 903 via the transistor (Qn) 904. The TN liquidcrystal generally operates in a mode in which light passes throughduring the period without applying a voltage, i.e., a so-called normallywhite mode.

In this case, as the signal line voltage Vd, a voltage, by which thetransmittance of light which passes through the TN liquid crystal isenhanced, is applied over several fields. When the horizontal scanningperiod has completed and the scanning line voltage Vg has been broughtto a low level, the transistor (Qn) 904 is turned off, thereby thesignal line voltage transferred to the pixel electrode 903 is held bythe storage capacitor 906 and the capacitance Cpix of the liquidcrystal. The pixel voltage Vpix shows voltage shifts called feed-throughvoltages via the gate-to-source capacity of the transistor (Qn) 904 at atime when the transistor (Qn) 904 is turned off. In FIG. 3, the voltageshifts are represented as Vf1, Vf2, Vf3. The amounts of the voltageshifts Vf1 to Vf3 can be decreased by designing the storage capacitor906 so as to stand at a large value.

The pixel voltage Vpix is held during the next field period until thescanning line voltage Vg is brought to the high level again and thetransistor (Qn) 904 is selected. The switching of the TN liquid crystalis created according to the held pixel voltage Vpix; that is, as shownas a light transmittance T1, the transmitted light of the liquid crystaltransitions from a dark state to a bright state. At this point in time,as shown in FIG. 3, the pixel voltages Vpix vary at the individualfields by ΔV1, ΔV2, ΔV3 respectively during the holding period. Thisresults from a fact that the capacity of the liquid crystal variesaccording to the response of the liquid crystal. To minimize thevariation, the storage capacitor 906 is generally designed in such a waythat it stands at a large value which is at least 2 to 3 times that ofthe pixel capacity Cpix. As explained above, the TN liquid crystal canbe driven by using the pixel circuit shown in FIG. 1.

As a technique having an effect achieved by using a method developed bycombining the overdrive system and the reset system, there is atechnique of modulating a common voltage (common electrode voltage (oropposing electrode voltage)) shown in Japanese Translation ofInternational Application (Kohyo) No. 2001-506376 (hereinafter referredto as “first publication”). FIG. 2C of the first publication is quotedas FIG. 5. In this technique, the common voltage, which is a voltage ata common electrode disposed so as to be opposite a pixel electrode, ismodulated in general. In FIG. 5, the upper graph shows a variation incommon voltage (VCG) with respect to time and the lower graph shows avariation in light transmittance (I) caused by the response of theliquid crystal with respect to time. That is, a voltage waveform 151represents the waveform of a voltage applied to the common electrode, alight intensity waveform 152 represents a light intensity waveformcorresponding to the waveform 151 with respect to time, and linesegments 153 to 156 represents pixel light intensity curves. Intechniques used prior to the use of this technique, driving during whicha common voltage is held at a constant value is conducted or commonreverse driving is conducted in which voltage varies so as to take ontwo values in a constant cycle represented as one frame cycle whichcomprises respective periods of t0 to t2 and t2 to t4 shown in FIG. 5.In the first publication, one frame cycle is divided into halves duringthe respective periods of t1 to t2 and t3 to t4, a voltage whoseamplitude is the same as that used in conventional common reversedriving is applied. On the other hand, during periods of t0 to t1 and t2to t3 of one frame cycle, a voltage higher than the amplitude of thecommon reverse such as a voltage higher than the amplitude of the commonreverse by a voltage generated during a black image is applied. In thistechnique, there is an effect that a voltage differential between thepixel electrode and the common electrode increases during the period oft0 to t1 over which a high voltage is applied to the common electrode,thereby the entire display region can be rapidly changed to a blackimage. That is, driving corresponding to the reset driving is performed.Moreover, even when image data is written into the pixel electrodeduring the period of t0 to t1, the writing is not observed on thedisplay since a potential difference between the pixel electrode and thecommon electrode is sufficiently large (for example, a voltage placedfor the black image or larger). After image data is written into theentire display region, the voltage at the common electrode is returnedto the amplitude of the common reverse with a timing of t1. As a result,the liquid crystal layer initiates its responses in such a way that itstransmittance varies according to respective gradation levels based onthe voltage stored in the pixel electrode. That is, at the time of theinitiation of the response, the state in which the voltage differentialis large always changes to a state in which voltage differentials arecoincide with voltages at the respective gradations. Therefore, a kindof overdrive occurs during the period of t0 to t1.

Here, it should be noted that the response time of liquid crystal isgenerally given by the following two expressions (see the Dictionary ofLiquid Crystal, p. 24, published by Baifukan Ltd., edited by the JapanSociety for the Promotion of Science, the 142nd Committee on OrganicMaterials for Information Science, the Group on Liquid Crystal, andhereinafter referred to as “third publication”): that is, in a riseresponse (on-time response) in which a voltage which is higher than athreshold voltage is applied to effect an on state, the followingexpression 1 is established:

$\begin{matrix}{\tau_{rise} = \frac{d^{2} \cdot \overset{\sim}{\eta}}{\Delta \; {ɛ \cdot \left( {V^{2} - V_{c}^{2}} \right)}}} & \left( {{Expression}\mspace{14mu} 1} \right)\end{matrix}$

On the other hand, in a fall response (off-time response) in which theapplied voltage which is higher than the threshold voltage is quicklybrought down to zero V, the following expression 2 is established:

$\begin{matrix}{\tau_{decay} = \frac{d^{2} \cdot \overset{\sim}{\eta}}{\pi^{2} \cdot \overset{\sim}{K}}} & \left( {{Expression}\mspace{14mu} 2} \right)\end{matrix}$

where d is the thickness of a liquid crystal layer, η is a rotationviscosity, Δε is dielectric anisotropy, V is an applied voltagecorresponding to each gradation level, Vc is a threshold voltage, and Kis a constant based on Frank elastic constant. In TN mode, K is given bythe following expression 3:

$\begin{matrix}{\overset{\sim}{K} = {K_{11} + {\frac{1}{4}\left( {K_{33} - {2 \cdot K_{22}}} \right)}}} & \left( {{Expression}\mspace{14mu} 3} \right)\end{matrix}$

where K₁₁ is the elastic constant of a spread, K₂₂ is the elasticconstant of a twist, and K₃₃ is the elastic constant of a bend. As isapparent from the expression 1, in the rise response (on-time response),the response time of liquid crystal depends on the reciprocal of thesquare of the value of an applied voltage. That is, the response time ofthe liquid crystal depends on the reciprocal of the square of the valueof a voltage which varies according to each gradation level. Because ofthis, the response time significantly varies according to the gradationlevels; when there is a ten-times voltage differential, a hundred-timesdifference in the response time occurs. On the other hand, even in thefall response (off-time response), there is a difference in the responsetime according to the gradation levels; however, the difference fallswithin an about double range.

According to the third publication, the response speed of the liquidcrystal is increased by the overdrive effect that a very high voltage isapplied at the time of the rise response (on-time response). Moreover,since every responses used for actual image displays are fall responses(off-time responses), a dependence on the gradation levels is remarkablylow. As a result, about the same response time can be achieved over allgradations.

However, the foregoing liquid crystal display apparatuses, that is, thedisplay apparatus using the overdrive, the display apparatus using thereset drive, the display apparatuses disclosed in the documents such asthe first publication, and so on have several problems.

A first problem is as follows: in the overdrive system, the riseresponse (on-time response) speed of the liquid crystal can beincreased, while the response speed is on the order of ten and severalmilliseconds to several tens of milliseconds at most due to limitedmaterials for the liquid crystal. Moreover, as described below, the fallresponse (off-time response) speed cannot be increased so much.

Such a problem can be solved by the following means. To increase theresponse speed of the liquid crystal itself, as is apparent from theexpressions 1 and 2, it is preferable to take effective measures such asthe following:

-   (1) decreasing the thickness d of the liquid crystal layer;-   (2) lowering the viscosity η;-   (3) enhancing the dielectric anisotropy Δε (only in the rise    (on-time) response);-   (4) increasing the applied voltage (only in the rise (on-time)    response); and-   (5) decreasing the elastic constants K₁₁ and K₃₃ and increasing the    elastic constant K₂₂ (only in fall (off-time) response). However,    with the item (1), to sufficiently achieve an optical effect, the    thickness of the liquid crystal layer can be decreased only within    the range of its constant relationship with a refractive index    anisotropy Δn. Moreover, with the items (2), (3), and (5), since all    viscosity, the dielectric anisotropy, and the elastic constants are    physical property values, these are highly dependent on the    materials of the liquid crystal and hence, it is difficult to set    these at values which exceed certain conditions. And further, it is    very difficult to significantly vary any one of the physical    property values and hence, it is difficult to achieve an effect on    the high-speed response expected from the expressions. For example,    although K₁₁, K₂₂, and K₃₃ are independent elastic constants, a    relationship K₁₁:K₂₂:K₃₃=10:5:14 is substantially established from    the measurement results on actual materials, so that these cannot be    always treated as independent constants. That is, from the    relationship and the expression 3, for example, a relationship    K=11·K₂₂/5 is established and therefore, only K₂₂ is an independent    constant. Because of this, these can be adjusted a little, but it is    difficult to achieve improvement above scores of percent. Still    further, with the item (4), the method for increasing the value of    the applied voltage also has a considerable limitation in terms of    power consumption and the increased production cost of the    high-voltage driving circuit. In addition, when the display    apparatus is driven by providing an active element such as a thin    film transistor, the response speed is limited by the withstand    pressure of the element. As described above, there is a considerable    limit to the fast response speed achieved by using those    conventional means including the overdrive in principle.

A second problem is that in the overdrive system, the rise response(on-time response) can be sped up but the fall response (off-timeresponse) can be hardly sped up. As is apparent from the expressions 1and 2, this is because the rise response (on-time response) depends onthe potential difference to effect the variation in the response timebut the fall response (off-time response) does not depend on thepotential difference. That is, the rise response (on-time response) canbe sped up by increasing the potential difference, but the fall response(off-time response) cannot. As a result, in the conventional overdrivesystem, the fall response (off-time response) not sped up dominantlydetermines the response speed of the entire system.

A third problem is that in the conventional overdrive system the voltagerequired for the overdrive is high. The video signals of the displayapparatus are high-frequency signals and hence, in the overdrive systemin which the voltages of the video signals are increased, powerconsumption, which is determined by the voltage and the frequency, hasbeen increased significantly. Moreover, since there is a need to producethe high-frequency high-voltage signals, it is difficult to use the samedriving IC and signal conditioning system as those of conventionaldisplay apparatuses, so that a need to use ICs fabricated by using aspecial process or expensive ICs has often arisen.

A fourth problem is that in the reset system, a method of applying resetsignals via a pixel switch has the disadvantages that the structure of adriving system becomes complex and power consumption is increased. Thatis, scanning for the writing of the video signals requires the drivingof scanning lines which is different in scanning period and scanningmethod. When the pixel switch is reset, a method for resetting allscanning lines together is often used instead of sequential scanning andhence, it becomes necessary to provide a structure where signals aresent together into the scanning system. Moreover, since the scanninglines are driven at the time of not only the writing of the videosignals but also the writing of the reset signals, the frequencies ofsignals for the scanning lines having the highest voltage amplitude inthe display apparatus are increased, thereby power consumption isincreased. As a result, it is desirable that the reset not be conductedvia the pixel switch.

A fifth problem is that in the reset system, the state of the displayconsiderably changes due to the reset of an excessive or short degree.This problem also holds true for the method described in the firstpublication which is created by combining the overdrive system and thereset system.

First, the reset is excessive, the initiation of the optical response ofthe liquid crystal after the reset becomes slow and abnormal opticalresponses are observed before the initiation of normal opticalresponses. This is because at the time of a transition from apredetermined alignment state realized by the reset to the normalresponse, a direction in which the liquid crystal operates during theresponse is not clear and hence, nonuniform and unstable responses areshown. An example of the abnormal optical responses is shown in FIG. 21.As shown in FIG. 21, when the reset is excessive, delays in the opticalresponses and abnormal displays (such as the transient rise intransmittance) develop.

On the other hand, in the reset system, the shortage of the reseteffects a situation where when the same data is written several times,the same transmittance cannot be sometimes obtained. When the reset isinsufficient, a predetermined alignment state is not completely realizedduring the reset, so that the response following the reset showstransmittance corresponding to the history of a previous frame. As aconsequence, a one-to-one correspondence is not established between theapplied voltage and the transmittance. Because of this, a desiredgradation cannot be attained or even when the same gradation isdisplayed, brightness varies greatly. The variation in the brightnessmay result in, for example, a difference between brightness caused bythe application of a positive signal voltage and brightness caused bythe application of a negative signal voltage, that is, flicker.

A sixth problem is that it is difficult to attain stable display over awide temperature range. This is because the viscosity η of the liquidcrystal is highly dependent on temperature and hence, the response speedof the liquid crystal is also highly dependent on temperature.Particularly, in the reset system and the method described in the firstpublication, when a temperature changes, the foregoing excessive orinsufficient reset develops clearly. As a result, the response speed isdecreased at low temperatures, which result in, for example, aconsiderable reduction in brightness. On the other hand, at hightemperatures, for example, the response speed at intermediate gradationdisplay is increased and the brightness is enhanced all over thedisplay, so that the display approaches a white image. Because of this,a phenomenon in which the entire display becomes whitish and so on takesplace. Furthermore, since the shortage of the reset occurs at lowtemperatures, the problem that the correspondence between the appliedvoltage and the transmittance is not established arises, thereby adesired gradation cannot be obtained or flicker is caused.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystaldisplay apparatus, which is capable of improving display performance,increasing a response speed, and improving temperature dependence andreliability, a driving method for the same, and a driving circuit forthe same.

Another object of the present invention is to provide a liquid crystaldisplay apparatus, which is capable of achieving a high-speed responseand a high light-use efficiency, operating at low power consumption,stabilizing images within one frame, eliminating image degradationcaused by the influence of history, and displaying sharp moving imageswithout developing blurred moving images during moving image display, adriving method for the same, and a driving circuit for the same.

Moreover, another object of the present invention is to provide a liquidcrystal display apparatus, which is capable of eliminating uneven andunstable liquid crystal responses resulting from reset driving and soon, producing an excellent display having a small change in displaydespite a change in ambient temperature, and exhibiting high reliabilityand which can be fabricated at low cost without requiring ahigh-performance IC for driving and a high-performance signal processingcircuit, a driving method for the same, and a driving circuit for thesame. For example, the object of the present invention is to provide aliquid crystal which is capable of eliminating flicker and so on,producing a smooth change in gradation, and exhibiting high reliabilityto a change in environment and which can be fabricated at low cost forthe entire display system.

Further, another object of the present invention is to provide ahigh-speed liquid crystal display apparatus capable of writing data byusing a frame frequency (of, for example, 70 Hz, 80 Hz, or 200 Hz) whichis higher than an ordinary frame frequency (of, for example, 60 Hz) or aframe frequency (of, for example, 120 Hz, 180 Hz, or 360 Hz) which is anintegral multiple of the ordinary frame frequency.

Still further, another object of the present invention is to provide aliquid crystal display apparatus capable of producing a field sequentialcolor display attained by dividing a display image into several colorimages, successively displaying the respective color images in timesequence, and lighting light sources having the same colors as those ofthe color images in synchronization with the color images. Moreparticularly, another object of the present invention is to provide aliquid crystal display apparatus capable of effecting field sequentialdriving in a TN type liquid crystal display mode. Moreover, anotherobject of the present invention is to provide a liquid crystal displayapparatus capable of effecting field sequential driving in a TN typeliquid crystal display mode even when the apparatus is a transmissivetype. Furthermore, another object of the invention is to provide aliquid crystal display apparatus capable of realizing field sequentialdriving in various liquid crystal display modes other than the TN typeliquid crystal display mode. In addition, another object of theinvention is to make these liquid crystal display apparatuses have ahigh efficiency in light utilization.

Referring to FIG. 9 and FIG. 12 of the embodiments of the presentinvention, a liquid crystal display apparatus according to a firstaspect of the present invention has a common electrode potentialcontrolling circuit (203) and a synchronizing circuit (204). The commonelectrode potential controlling circuit (203) changes the potential of acommon electrode (215) into a pulse shape after a scanning signaldriving circuit (202) scans the entire scanning electrodes (212) totransmit a video signal to a pixel electrode (214).

Referring to FIG. 10 and FIG. 13 of the embodiments of the presentinvention, a liquid crystal display apparatus according to a secondaspect of the present invention has a storage capacitance electrodepotential controlling circuit (205) and a synchronizing circuit (204).The storage capacitance electrode potential controlling circuit (205)changes the potential of a storage capacitance electrode (216) into apulse shape after a scanning signal driving circuit (202) scans theentire scanning electrodes (212) to transmit a video signal to a pixelelectrode (214).

In the liquid crystal display apparatus according to the first aspectand the second aspect of the present invention, the comparison of thedata and the variation in the potentials is performed one by one or isperformed by using an LUT (look-up tables, correspondence table)prepared in advance.

In the liquid crystal display apparatus according to the presentinvention, the comparison of the data and the variation in thepotentials is performed by using an LUT (look-up tables, correspondencetable) prepared in advance according to the polarity of the videosignals with respect to the common electrodes and the type of colorsignals to be displayed.

In the liquid crystal display apparatus according to the presentinvention, an LUT (look-up tables, correspondence table) is used inwhich a relationship between the video signals and the brightness ofgradation obtained from the video signals is set up. The LUT varies withthe polarity of the video signals and the type of the color signals tobe displayed.

Referring to FIG. 11 and FIG. 14 of the embodiments of the presentinvention, a liquid crystal display apparatus according to a thirdaspect of the invention has a common electrode potential controllingcircuit (203), a storage capacitance electrode potential controllingcircuit (205), and synchronizing circuit (204). The common electrodepotential controlling circuit (203) changes the potential of a commonelectrode (215) into a pulse shape after a scanning signal drivingcircuit (202) scans the entire scanning electrodes (212) to transmit avideo signal to a pixel electrode (214). The storage capacitanceelectrode potential controlling circuit (205) changes the potential of astorage capacitance electrode (216) into a pulse shape after a scanningsignal driving circuit (202) scans the entire scanning electrodes (212)to transmit a video signal to a pixel electrode (214).

Referring to FIG. 9 and FIG. 12 of the embodiments of the presentinvention, a liquid crystal display apparatus according to a fourthaspect of the invention has a common electrode potential controllingcircuit (203), a synchronizing circuit (204), and a plurality of commonelectrodes (215) electrically isolated from one another. The commonelectrode potential controlling circuit (203) changes the potential ofthe common electrodes (215), which correspond to scanning electrodes(212) scanned by a scanning signal driving circuit (202), into a pulseshape after the scanning signal driving circuit (202) scans part of thescanning electrodes (212) to transmit video signals to pixel electrodes(214).

As shown in FIG. 10 and FIG. 13, a liquid crystal display apparatusaccording to a fifth aspect of the invention has a storage capacitanceelectrode potential controlling circuit (205), a synchronizing circuit(204), and a plurality of storage capacitance electrodes (216)electrically isolated from one another. The storage capacitanceelectrode potential controlling circuit (205) changes the potential ofthe storage capacitance electrodes (216), which correspond to scanningelectrodes (212) scanned by a scanning signal driving circuit (202),into a pulse shape after the scanning signal driving circuit (202) scanspart of the scanning electrodes (212) to transmit video signals to pixelelectrodes (214).

As shown in FIG. 11 and FIG. 14, a liquid crystal display apparatusaccording to a sixth aspect of the invention has a common electrodepotential controlling circuit (203), a storage capacitance electrodepotential controlling circuit (205), a synchronizing circuit (204), aplurality of common electrodes (215) electrically isolated from oneanother, and a plurality of storage capacitance electrodes (216)electrically isolated from one another. The common electrode potentialcontrolling circuit (203) changes the potential of the common electrodes(215), which correspond to scanning electrodes (212) scanned by ascanning signal driving circuit (202), into a pulse shape after thescanning signal driving circuit (202) scans part of the scanningelectrodes (212) to transmit video signals to pixel electrodes (214).The storage capacitance electrode potential controlling circuit (205)changes the potential of the storage capacitance electrodes (216), whichcorrespond to the scanning electrodes (212) scanned by the scanningsignal driving circuit (202), into a pulse shape after the scanningsignal driving circuit (202) scans part of the scanning electrodes (212)to transmit video signals to the pixel electrodes (214).

In the liquid crystal display apparatus according to the presentinvention, the potentials of the common electrodes (215) changed into apulse shape and the potentials of the storage capacitance electrode(216) changed into a pulse shape are potentials by which a display on adisplay unit (200) is not reset.

In the liquid crystal display apparatus according to the presentinvention, the potentials of the common electrodes (215) vary between atleast three potentials and preferably between at least four potentials.Moreover, the potentials of the storage capacitance electrodes (216)vary between at least three potentials and preferably between at leastfour potentials.

In the liquid crystal display apparatus according to the presentinvention, the potentials of the common electrodes (215) changed into apulse shape or the potentials of the storage capacitance electrodes(216) are changed into a pulse shape to temporarily increase a potentialdifference between the potentials of the pixel electrodes (214) and thepotentials of the common electrodes (215) or the potentials of thestorage capacitance electrodes (216).

In the liquid crystal display apparatus according to the presentinvention, the potentials of the video signals are different from thepotentials of video signals in a stable display state brought aboutduring static driving in consideration of the response characteristicsof the display unit (200) during charge holding type driving.

In the liquid crystal display apparatus according to the presentinvention, the potentials of the video signals are determined by makinga comparison between data held by individual pixels before the writingof the video signals and display data to be newly displayed.

In the liquid crystal display apparatus according to the presentinvention, a field response type substance is sandwiched between thepixel electrodes (214) of the display unit (200) and the commonelectrodes (215) of the display unit (200). Moreover, the field responsetype substance is made of a liquid crystal substance.

In the liquid crystal display apparatus according to the presentinvention, the liquid crystal substance is a nematic liquid crystalwhich effects twisted nematic alignment.

And further, between the twist pitch p (μm) of the nematic liquidcrystal and the average thickness d (μm) of the nematic liquid crystallayer, the relationship p/d<20 is set up. It is preferable that therelationship p/d<8 be set up between the twist pitch p (μm) of thetwisted nematic liquid crystal and the average thickness d (μm) of thetwisted nematic liquid crystal substance layer.

In the liquid crystal display apparatus according to the presentinvention, the twisted nematic liquid crystal substance is stabilized bya polymer liquid crystal having a mostly continuously twisted structure.

In the liquid crystal display apparatus according to the presentinvention, the liquid crystal substance is used in an electricallycontrolled birefringence mode.

In the liquid crystal display apparatus according to the presentinvention, the liquid crystal substance has a pie-type alignment(bend-type alignment). Moreover, it is preferable that the liquidcrystal substance be provided with an optical compensation plate andused in an OCB (optically compensated birefringence or opticallycompensated bend) mode.

In the liquid crystal display apparatus according to the presentinvention, the liquid crystal substance is used in a VA (verticalalignment) mode in which homeotropic alignment is developed. Andfurther, it is preferable that a wide viewing angle be secured byproviding a multidomain and so on.

In the liquid crystal display apparatus according to the presentinvention, the liquid crystal substance is used in an IPS (in-planeswitching) mode in which the response of the substance is made by anelectric field developed parallel to the substrate surface.

In the liquid crystal display apparatus according to the presentinvention, the liquid crystal substance is used in a FFS (fringe fieldswitching) mode or an AFFS (advanced fringe field switching) mode.

In the liquid crystal display apparatus according to the presentinvention, the liquid crystal substance is a ferroelectric liquidcrystal substance, an antiferroelectric liquid crystal substance, or aliquid crystal substance which produces an electroclinic type response.

In the liquid crystal display apparatus according to the presentinvention, the liquid crystal substance is a cholesteric liquid crystalsubstance.

In the liquid crystal display apparatus according to the presentinvention, the alignment of the liquid crystal substance is stabilizedby polymer to the alignment in the state being applied no voltage orallied a low voltage.

In the liquid crystal display apparatus according to the presentinvention, a stereoscopic display is produced by using a lenticular lenssheet, a lenticular film, or a double-sided prism sheet and by sendingvideo signals for one eye to the individual pixels arranged parallel toone another, that is, by separately sending video signals for the righteye and video signals for the left eye to these. And further, it ispreferable that the stereoscopic display is produced by using a scanbacklight produced by alternately sending two beams of light from twolight sources to a backlight and at the same time, by performingswitching with time between the video signals for the right eye and thevideo signals for the left eye through the use of a frequency which ismore than twice as high as that used conventionally.

In the liquid crystal display apparatus according to the presentinvention, the video signals are divided into a plurality of color videosignals corresponding to a plurality of colors, the light sources, whichcorrespond to the colors, are synchronized with the color video signalswith a predetermined phase difference provided, and the color videosignals are displayed in sequence.

In the liquid crystal display apparatus according to the presentinvention, video signals consist of video signals for the right eye andvideo signals for the left eye. The individual video signals for one eyeare divided into a plurality of color video signals corresponding to aplurality of colors, and light sources, which are disposed at two placesand correspond to the colors, are synchronized with the video signalsfor one eye with a predetermined phase difference provided and are alsosynchronized with the color video signals. Then the video signals forone eye are sent in sequence as the divided color video signals fordisplay.

In the liquid crystal display apparatus according to the presentinvention, the pixel switch comprises an amorphous silicon thin filmtransistor, a polycrystalline silicon thin film transistor, asingle-crystalline silicon thin film transistor including a SOI (siliconon insulator), or the like.

In the liquid crystal display apparatus according to the presentinvention, the polarity of the video signals is reversed with apredetermined timing. Among the varying potentials of the commonelectrodes, one or two potentials whose application period is longerthan those of the remaining potentials are nearly equal to a potentialintermediate between the maximum and the minimum potentials of allpotentials applied as the video signals.

In the liquid crystal display apparatus according to the presentinvention, the polarity of the video signals is reversed with apredetermined timing. Among the varying potentials of the commonelectrodes, one or two potentials whose application period is longerthan those of the remaining potentials are nearly equal to a potentialintermediate between the maximum and the minimum potentials of allpotentials which can be applied as the video signals.

In the liquid crystal display apparatus according to the presentinvention, the potentials of the common electrodes provided immediatelybefore the scanning signal driving circuit (202) starts to scan theinitial electrode of the scanning electrodes (212) are equal to thepotentials of the common electrodes to be changed into a pulse shapeimmediately after the scanning signal driving circuit (202) has scannedall scanning electrodes (212) and has transmitted video signals to thepixel electrodes (214).

In the liquid crystal display apparatus according to the presentinvention, the potentials of the common electrodes provided immediatelybefore the scanning signal driving circuit (202) starts to scan theinitial electrode of the scanning electrodes (212) are different fromthe potentials of the common electrodes to be changed into a pulse shapeimmediately after the scanning signal driving circuit (202) has scannedall scanning electrodes (212) and has transmitted video signals to thepixel electrodes (214).

In the driving method for the liquid crystal display apparatus accordingto the present invention, the common electrode has four potentials. Thefirst potential is the potential of the common electrode developed at atime period over which the scanning signal driving circuit (202) scansthe scanning electrode (212) to transmit a video signal having onepolarity of the video signal which is periodically reversed. The secondpotential is the potential of a pulse height portion which is formedwhen the potential of the common electrode (215) is changed into a pulseshape following the development of the first potential. The thirdpotential is not only a potential which is developed after the potentialof the common electrode (215) has been changed into a pulse shapefollowing the development of the second potential but the potential ofthe common electrode developed at a time period over which the scanningsignal driving circuit (202) scans the scanning electrode (212) totransmit a video signal having the other polarity of the video signalwhich is periodically reversed. The fourth potential is the potential ofthe pulse height portion which is formed when the potential of thecommon electrode (215) is changed into a pulse shape following thedevelopment of the third potential.

In the driving method for the liquid crystal display apparatus accordingto the present invention, the common electrode has six potentials. Thefirst potential is the potential of the common electrode developed at atime period over which the scanning signal driving circuit (202) scansthe scanning electrode (212) to transmit a video signal having onepolarity of the video signal which is periodically reversed. The secondpotential is the potential of the pulse height portion which is formedwhen the potential of the common electrode (215) is changed into a pulseshape following the development of the first potential. The thirdpotential is a potential which is developed after the potential of thecommon electrode (215) has been changed into a pulse shape following thedevelopment of the second potential. The fourth potential is thepotential of the common electrode which is developed at a time periodover which the scanning signal driving circuit (202) scans the scanningelectrode (212) to transmit a video signal having the other polarity ofthe video signal which is periodically reversed. The fifth potential isthe potential of the pulse height portion which is formed when thepotential of the common electrode (215) is changed into a pulse shapefollowing the development of the fourth potential. The sixth potentialis a potential which is developed after the potential of the commonelectrode (215) has been changed into a pulse shape following thedevelopment of the fifth potential.

The liquid crystal display apparatus according to the present inventionhas a light irradiating unit, which irradiates the display unit withlight and a synchronizing circuit which synchronizes the intensity oflight from the light irradiating unit with the video signal so as tohave a predetermined phase for modulation.

The liquid crystal display apparatus according to the present inventionhas a light irradiating unit, which irradiates the display unit withlight and a synchronizing circuit which synchronizes the color of lightfrom the light irradiating unit with the video signal so as to have apredetermined phase for change.

In the driving method for the liquid crystal display apparatus accordingto the present invention, when a timing, at which the intensity of lightfrom the light irradiating unit is modulated or the color of the lightis changed, is divided into individual fields or a plurality of colors,the timing is set after the division of subfields corresponding to thecolors, that is, immediately before a video signal of the next field iswritten.

In the liquid crystal display apparatus according to the presentinvention, the potential of the video signals is determined by making acomparison of data held by the pixels before the writing of the videosignals, a variation in the potentials of the pixel electrodesassociated with a variation in the potentials of the common electrodes(215) changed into a pulse shape, the potentials of the storagecapacitance electrodes (216) changed into a pulse shape, or thepotentials of both the common electrodes (215) and the storagecapacitance electrodes (216), and display data to be newly displayed.And further, data to be newly displayed is determined by taking intoaccount the variation in the potentials of the pixel electrodesresulting from a capacitance coupling associated with the polarityreversal of data signals as well.

By changing the potentials of the common electrodes, the potentials ofthe storage capacitance electrodes, or the potentials of both of theseto the pulse from after the scanning signal driving circuit has scannedthe entire scanning electrodes and transmitted video signals to thepixel electrodes, the potential difference between the pixel electrodesand the common electrodes developed after the transmission of the videosignals varies at the individual time periods, that is, before and afterthe change into the pulse shape and at the time of formation of thepulse height portion (however, the potential difference before thechange into the pulse shape may become equal to that after the changeinto the pulse shape). As a result, it is possible to adjust a change inthe state and the response speed of the display substance at theindividual time period, thereby the response speed can be increased.Moreover, it is also possible to decrease the response speed asnecessary. In particular, a temporary increase in the potentialdifference between the potentials of the pixel electrodes and thepotentials of the common electrodes is highly effective in increasingthe response speed.

And further, the provision of the electrically isolated commonelectrodes, storage capacitance electrodes, or both of these allows onlypart of the display unit to be changed into a pulse shape. As aconsequence, regions having any shape within the display unit can bechanged into a pulse shape in any order, so that the state of theresponse can be changed at each region.

By setting the potentials of the common electrodes, the potentials ofthe storage capacitance electrodes, or the potentials of both of theseat a potential at which reset is not allowed when these are changed intoa pulse shape, the following action is effected. In general, the resetbrings the liquid crystal alignment into a predetermined state. As aresult, when the transition from the predetermined state to anotherstate is processed, delay often develops. However, by setting thesepotentials at the potential at which the reset is not allowed, thedevelopment of the delay can be prevented, so that the faster responsespeed can be attained.

The delay developed due to the transition from the reset state isdivided into two types of delays. The first delay is a delay developedby the fact that when the transition from the reset state to anotherstate is made, a direction in which the display substance should respondis not determined promptly due to fluctuation and so on of the substanceitself. In this delay, an optical state including transmission andreflection of light is still in about the same state as the reset state,so that a time delay develops until changes in the optical state startto occur. The second delay is a delay developed by the fact that whenthe transition from the reset state to another state is made, thedisplay substance temporarily responds in directions other than itsobjective direction such as the reverse direction. In this delay, theoptical state including the transmission and reflection of light aredifferent from that in the reset state, while an optical state differentfrom a desired control state arises. During a time period over which achange from a response in the undesired direction to the response in thedesired direction is performed, there is a time delay which is longerthan the first delay. Moreover, a phenomenon which occurs morefrequently is as follows: in a system in which the second delaydevelops, the first delay also develops simultaneously and hence, thedelay time becomes longer.

By setting the potentials of the common electrodes, the potentials ofthe storage capacitance electrodes, or the potentials of both of theseat the potential at which the reset is not allowed, these two delays andthe combined delay are eliminated, thereby a response speed expectedoriginally can be achieved.

Furthermore, since the reset is not allowed, the dependence of thedisplay on the excess of deficiency of the reset is eliminated. Becauseof this, it becomes possible to attain a stable display over a widetemperature range.

By changing the potentials of the common electrodes or the potentials ofthe storage capacitance electrodes into the pulse shape so as totemporarily increase the potential difference between the potentials ofthe pixel electrodes and the potentials of the common electrodes or thepotentials of the storage capacitance electrodes, an overdrive(feed-forward) effect can be secured without the operation of the videosignals. In the invention, in contrast to conventional overdriving inwhich video signals are operated, it is possible to simultaneouslyproduce the overdrive effect on the entire region electricallyinterconnected.

And further, by performing overdriving on the video signals themselvesas well, a two-step fast response speed can be achieved in combinationwith the foregoing effect. This overdriving is different from theconventional overdriving in that since there is no need to increase theresponse speed only by the overdriving, only the application of arelatively small voltage is necessary.

On the other hand, a fall response (off-time response) cannot be sped uponly by the foregoing method. Because of this, in the twisted nematicliquid crystal, a torque required to return to the twisted state isincreased by setting a twist pitch p at p/d<8. Moreover, in all liquidcrystal display modes including the twisted nematic liquid crystaldisplay mode, a torque required to return to the alignment applying novoltage resulting from polymer stabilization and so on is increased,thereby the fall response (off-time response) is sped up.

To make a comparison between the fast response speed attained in theinvention and conventional response speeds, a comparison betweendifferences in response times will be made theoretically. In thiscomparison, twisted nematic liquid crystal display apparatuses are used.As the response times, two response times will be examined whichcorrespond to the rise response (on-time response) and the fall response(off-time response) described in the item “Technical Background of theInvention.” In FIG. 41A and FIG. 41B, the outline of ways to determinethe on-time response and the off-time response of the twisted nematicliquid crystal which produces a normally white image is shown. FIG. 41Aand FIG. 41B are graphs in which horizontal axes represent individualgradation levels and vertical axes represent brightness. FIG. 41Arepresents a rise response (on-time response) and FIG. 41B represents afall response (off-time response). As shown in FIG. 41A, in the riseresponse, the on-time response is defined as a response time over whichbrightness varies from the highest gradation level to individualgradation levels. Also, as shown in FIG. 41B, in the fall response, theoff-time response is defined as a response time over which thebrightness varies from lowest gradation level to individual gradationlevels. In the twisted nematic liquid crystals other than the normallywhite image liquid crystal and the other liquid crystal display modes,the highest-level brightness and the lowest-level brightness may betransposed. The on-time responses and the off-time responses of the fourtypes of twisted nematic liquid crystal display apparatuses different indriving methods are schematically shown in the drawings in whichhorizontal axes represent individual gradation levels and vertical axesrepresent response times. The liquid crystal display apparatus shown inthe drawing is as follows: (1) the liquid crystal display apparatususing normal driving (FIG. 42); (2) the liquid crystal display apparatususing an overdrive system (feedforward driving) (FIG. 43); (3) themethod described in the foregoing first publication (JapaneseTranslation of International Application (Kohyo) No. 2001-506376), i.e.,the liquid crystal display apparatus using a driving method which isdeveloped by combining the overdrive system and the reset system (FIG.44); and (4) the liquid crystal display apparatus according to thepresent invention (FIG. 45).

In the normal driving shown in FIG. 42, the speed of the on-timeresponse (indicated by a broken line) is high during the application ofa high voltage but is extremely low during the application of a lowvoltage. This response approximately adheres to the expression (1).However, the off-time response (indicated by a solid line) takes thesame time over almost all the voltage range (in actuality, the responsetime varies with voltages; however, the response time often falls withina range which is nearly double at most. As a result, therate-determining step of the response speed of the display apparatus (astep in which a dominant factor, which determines a reaction rate, ispresent: in this case, of the on-time and off-time responses, one whosespeed is slower is the dominant factor) is indicated by a dotted line inFIG. 42 and shows a slow response in a low voltage range. In thisfigure, a voltage represented at a point where the on-time response andthe off-time response intersect with each other is twice the square rootof 2 of a threshold voltage Vtc in an ideal state in which the voltageadheres to the expressions (1) and (2); for example, when Vtc=1.5V, thevoltage is a little more than 2V.

In the overdriving shown in FIG. 43, the on-time response (indicated bya broken line) is sped up when compared with the on-time response of thenormal driving indicated by an alternate long and short dashed line inFIG. 42. However, since the off-time response (indicated by a solidline) is about the same, its rate-determining step is indicated by thatof a dotted line in FIG. 43. That is, at a voltage which is higher thana voltage indicated at the intersection point of the on-time responseand the off-time response, its response time is the same as that of thenormal driving. At a voltage which is lower than a voltage indicated atthe intersection point, its response speed is sped up. As describedabove, an effect at the high voltage side is small but at the lowvoltage side, the longest response time is taken, thereby a display canbe considerably improved by overdriving. However, when a high voltage isexcessively applied during the overdriving, a response delay which isthe same as the transition from the reset state described above developsand in particular, the off-time response becomes slow.

In the method described in the first publication (Japanese Translationof International Application (Kohyo) No. 2001-506376) shown in FIG. 44,that is, in the driving method developed by approximately combining theoverdrive system and the reset system, since a reset state is effectedonce on the entire display, the on-time response is produced only at thepoint of the reset. That is, the response time is approximatelydetermined by the off-time response (indicated by a solid line) andhence, a rate-determining step represented a broken line isapproximately determined only by the off-time response. When comparedwith an off-time response produced by the normal driving indicated by abroken line in FIG. 48, the off-time response of this method (indicatedby a solid line) is slower because a delay is developed by a transitionresulting from the reset state. However, since there is no slow responseon a low voltage side, the largest length of the response time is muchshorter than that of the normal driving and the response speed is higherthan that achieved by the overdriving. On the other hand, on a highvoltage side, the off-time response is slower than those of the normaldriving and the overdriving, while the sum of the on-time response timeand the off-time response time, which is frequently used as a responsetime, is shorter than those of the normal driving and the overdrivingsince the on-time response hardly contributes to it.

In the liquid crystal display apparatus according to the presentinvention shown in FIG. 45, since a variation in the response speed,which corresponds to that achieved by the overdriving, is made through atwo-step effect achieved by the overdriving and a change into the pulseshape, the on-time response (indicated by a broken line) is sped up whencompared with that of the conventional overdriving (FIG. 43). Andfurther, since a state in which no voltage is applied is stabilized, atorque, which is required to return to the state in which no voltage isapplied, is high, the off-time response (indicated by a solid line) isalso sped up. Moreover, since a change in potential is implemented tosecure a state in which the reset does not occur, the delay associatedwith the transition from the reset state shown in FIG. 44 does notoccur. As a result, among the four liquid crystal display apparatuses,the display apparatus according to the present invention has the fastestresponse speed. In these cases, only the explanation for on-timeresponses and the off-time responses have been given, while it is amatter of course that responses of intermediate gradation levels arealso sped up.

A first effect of the liquid crystal display apparatus according to thepresent invention is that the response speed of the display substancecan be increased.

This is because a speedup, which corresponds to a two-step overdrivecomprising the overdrive of the video signals and the change into thepulse shape at the common electrodes or the storage capacitanceelectrodes after the writing of the video signals, is achieved at thetime of the rise. And further, this is because the delay is notdeveloped by setting the potential and the variation in the potential ata range in which the display substance is not reset at these steps.Moreover, this is because it is possible to increase the torque at thetime of the fall and to effect a change to the state in which no voltageis applied at high speed. This effect can be achieved by the control ofthe twist pitch, the polymer stabilization, the control of the electricfield, the control of interface alignment, and so on. That is, in theliquid crystal display according to the present invention, the responsespeed can be sped up at all steps including the rise response, the fallresponse, and the intermediate gradation response.

A second effect of the invention is that the high-reliability liquidcrystal display apparatus can be obtained which is capable of producingan excellent display even when the ambient temperature changes.

This is because the response speed of the liquid crystal is high andunstable alignment states such as bounce do not arise. In particular,this is due to the variation in the potentials at which the reset doesnot occur.

A third effect of the invention is that the liquid crystal displayapparatus can be obtained which has high light-use efficiency and lowpower consumption.

This is because first, the optical response of the liquid crystal issped up to reach stable transmittance quickly and secondly, the voltagerequired for the overdrive of the high-frequency video signals is low toperform the two-step overdrive and hence, power consumption can bereduced when compared with that of the conventional overdrive system.

A fourth effect of the invention is that the liquid crystal displayapparatus can be obtained in which stable images can be generated in oneframe and there is no degradation in image (variations in gradation andflicker) resulting from histories.

This is because response delays such as bounces and delays do notdevelop and the video signals by which desired display states can beobtained are produced by using a comparison computing unit or thelook-up table (LUT). In particular, this is because the comparisonbetween the data held by the individual pixels before the writing of thevideo signals, the variation in the potentials of the pixel electrodesassociated with the variation in the potentials of the common electrodeschanged into a pulse shape, the potentials of the storage capacitanceelectrodes (216) changed into a pulse shape, or the potentials of bothof these, and the display data to be newly displayed is made. Thevariation in the potentials of the common electrodes includes thevariation in the potentials of the pixel electrodes effected at the timeof the polarity reversal when the display apparatus is driven byreversing the polarity of the potentials of the common electrodes.Moreover, this is because the data to be newly displayed is determinedin consideration of the polarity reversal of the data signals, that is,the variation in the potentials of the pixel electrodes resulting fromthe capacitance coupling associated with the switching of the frames andso on. Through the waveform application taking into account suchvariation, the development of variations in gradation and flicker arenot observed.

A fifth effect of the invention is that the liquid crystal displayapparatus in which moving image blurring does not develop can beprovided.

This is because an excellent display can be produced by combining fieldsequential driving and the driving method according to the presentinvention. That is, this is because moving image blurring resulting fromholding type display is improved by switching the light sources throughthe use of a frequency which is higher than ordinary ones. And further,when the light sources are lit only in a certain period during thesubframe, a response close to that of an impulse type display apparatuscan be achieved, so that moving image blurring does not further develop.

A sixth effect of the invention is that it is possible to implement theoverdrive type display apparatus which has a simple system configurationand which is less expensive.

This is because there is no need to compare data on all colors of theprevious screen and data on all colors of the next screen and only dataon a certain color (or one color made by combining a plurality ofcolors) of the previous screen and data on a certain color (or one colormade by combining a plurality of colors) of the next screen can becompared through the adoption of the field sequential system. As aresult, the required memory is reduced in size and a small comparisoncomputing unit and small LUTs used at one time can be used.

In addition, another reason is that since the driving corresponding tothe two-step overdriving is performed, the voltage for the overdrivingto the video signals is lower than that of the conventional overdrivesystem. Among signals used in liquid crystal display apparatuses, videosignals have high frequencies and in conventional overdrive systems, thevoltages of high-frequency video signals are high. Because of this,conventional driving ICs have been unable to be used and there has beena necessity to use expensive driving ICs requiring a specialmanufacturing process and so on. Moreover, ICs, which generate videosignals, are required to address special uses as well. In the system ofthe invention, since the voltage for the overdriving is lower than thatfor the conventional overdriving, there is no need to use special ICs,so that it is possible to check an increase in the production cost ofthe liquid crystal display apparatus according to the present invention.

A seventh effect of the invention is that a stereoscopic display liquidcrystal display apparatus having a high degree of a sense of realism canbe obtained. This is because a high degree of color reproducibility isachieved by using LEDs and so on. Moreover, another reason is thatstereoscopic images can be displayed without spatial division and colordisplay can be produced without spatial division. As a result, a liquidcrystal display apparatus having far more pixels can be easilyimplemented when compared with conventional ones and a sense of realismcan be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an exemplary pixel circuit included in aconventional liquid crystal display apparatus;

FIG. 2 is a view showing an equivalent circuit of a TN liquid crystal;

FIG. 3 is a timing chart of the driving of the TN liquid crystal of theconventional liquid crystal display apparatus;

FIG. 4 is a graph showing the effect of conventional reset driving inwhich a dotted line represents normal driving and a solid linerepresents a variation in light intensity of driving effected by thereset driving;

FIG. 5 is a graph for explaining conventional driving performed bymodulating common voltage in which an upper graph represents a waveformof a voltage applied to a common electrode and a lower graph representslight intensity;

FIG. 6 is a view showing a relationship between wiring electricallyconnected to a certain pixel and potential;

FIG. 7 is a graph showing variations in potentials of an opposingelectrode and a storage capacity line with respect to time and avariation in a potential of a liquid crystal capacitor with respect totime which are effected when the potentials of the opposing electrodeand the storage capacity line are determined by a time constant circuit;

FIG. 8 is a graph showing an exemplary LUT with respect to the polarityof individual color signals and video signals used in simple systems;

FIG. 9 is a view showing a configuration of a liquid crystal displayapparatus according to a first embodiment of the present invention;

FIG. 10 is a view showing a configuration of a liquid crystal displayapparatus according to a second embodiment of the invention;

FIG. 11 is a view showing a configuration of a liquid crystal displayapparatus according to a third embodiment of the invention;

FIG. 12 is a view showing an exemplary configuration of a display unitaccording to the present invention;

FIG. 13 is a view showing an exemplary configuration of a display unitaccording to the present invention;

FIG. 14 is a view showing an exemplary configuration of a display unitaccording to the present invention;

FIG. 15 is a view showing an exemplary timing according to the firstembodiment of the invention;

FIG. 16 is a view showing an exemplary waveform according to the firstembodiment of the invention;

FIG. 17 is a view showing an exemplary order used for scanningelectrically isolated electrodes according to the fourth to sixthembodiments of the invention;

FIG. 18 is a view showing an exemplary shape of electrically isolatedelectrodes of display units according to the fourth to sixth embodimentsof the invention;

FIG. 19 is a view showing an exemplary display for a cellular telephoneto which the fourth to sixth embodiments of the invention are applied;

FIG. 20 is a view showing an exemplary arrangement of a plurality ofelectrically isolated common electrodes and a plurality of electricallyisolated storage capacitance electrodes of the display units accordingto the fourth to sixth embodiments of the invention;

FIG. 21 is a graph showing a variation in transmittance with respect totime shown in a case where a change into a pulse shape, which has thesame effect as that of the conventional reset, is provided;

FIG. 22 is a graph showing a variation in transmittance with respect totime shown in a case where a change into a pulse shape is not resetaccording to the present invention is provided;

FIG. 23 is a block diagram showing an exemplary driving device whichdrives liquid crystal display apparatuses according to the twelfth andthirteenth embodiments of the invention;

FIG. 24 is a graph showing a relationship between twist pitch/thicknessand a gradient at a transmittance of 50% during a fall responseaccording to a fifteenth embodiment of the invention;

FIG. 25 is a perspective view of a lenticular lens sheet (lenticularfilm);

FIG. 26 is a perspective view of a double-sided prism sheet;

FIG. 27 is a schematic diagram of an entire field sequential displaysystem according to a twenty-first embodiment of the invention;

FIG. 28 is a graph showing exemplary waveforms according to atwenty-fourth embodiment of the invention;

FIG. 29 is a graph showing exemplary waveforms according to atwenty-fifth embodiment of the invention;

FIG. 30 is a block diagram of an example of a liquid crystal displayapparatus according to a thirtieth embodiment of the invention;

FIG. 31 is a block diagram of another example of the liquid crystaldisplay apparatus according to the thirtieth embodiment of theinvention;

FIG. 32 is a block diagram of another example of the liquid crystaldisplay apparatus according to the thirtieth embodiment of theinvention;

FIG. 33 is a graph showing an exemplary waveform produced by digitaldriving of a liquid crystal display apparatus according to athirty-sixth embodiment of the invention;

FIG. 34 is a graph showing another exemplary waveform produced by thedigital driving of the liquid crystal display apparatus according to thethirty-sixth embodiment of the invention;

FIG. 35 is a view showing an exemplary PenTile arrangement;

FIG. 36(A) is a graph showing measurement results of variations inpotential and transmittance with respect to time in an example of theinvention;

FIG. 36(B) is a graph showing measurement results of variations inpotential with respect to time in an example of the invention;

FIG. 36(C) is a graph showing measurement results of variations inpotential with respect to time in an example of the invention;

FIG. 36(D) is a graph showing measurement results of variations intransmittance with respect to time in an example of the invention;

FIG. 37 is a graph showing a variation in transmittance with respect totime measured by changing temperature in the example of the invention;

FIG. 38 is a graph showing a variation in transmittance with respect totime measured by changing temperature in a comparative example;

FIG. 39 is a graph showing the dependence of integrated lighttransmittance on temperature in the example and comparative example ofthe invention;

FIG. 40 is a graph showing the dependence of a contrast ratio andintegrated light transmittance on a driving frequency in the example andcomparative example of the invention;

FIG. 41(A) is a view showing an outline of a method for determining anon-time response and an off time response of a twisted nematic liquidcrystal during a normally white image;

FIG. 41(B) is a view showing an outline of a method for determining anoff-time response of a twisted nematic liquid crystal during a normallywhite image;

FIG. 42 is a conceptual view showing an exemplary response time of aliquid crystal display apparatus using a normal driving method;

FIG. 43 is a conceptual view showing an exemplary response time of aliquid crystal display apparatus using overdrive;

FIG. 44 is a conceptual view showing an exemplary response time of aliquid crystal display apparatus using a driving method described in thefirst publication (Japanese Translation of International Application(Kohyo) No. 2001-506376), i.e., a driving method developed by roughlycombining overdrive and reset;

FIG. 45 is a conceptual view showing an exemplary response time of aliquid crystal display apparatus according to the present invention;

FIG. 46 is a sectional view showing a sectional structure of aplanar-type polycrystalline silicon TFT switch used in a first exampleof the invention;

FIG. 47(A) is a sectional view of a display panel substrate of theinvention illustrated in the order of its main production steps;

FIG. 47(B) is a sectional view of a display panel substrate of theinvention illustrated in the order of its main production steps;

FIG. 47(C) is a sectional view of a display panel substrate of theinvention illustrated in the order of its main production steps;

FIG. 47(D) is a sectional view of a display panel substrate of theinvention illustrated in the order of its main production steps;

FIG. 48(A) is a sectional view of the display panel substrate of theinvention illustrated in the order of its main production steps;

FIG. 48(B) is a sectional view of the display panel substrate of theinvention illustrated in the order of its main production steps;

FIG. 48(C) is a sectional view of the display panel substrate of theinvention illustrated in the order of its main production steps; and

FIG. 48(D) is a sectional view of the display panel substrate of theinvention illustrated in the order of its main production steps.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, embodiments of the present invention will be described in detailwith reference to the accompanying drawings.

First, a first embodiment of the present invention will be describedwith reference to FIG. 9 and FIG. 12. A liquid crystal display apparatusaccording to the first embodiment has a display unit 200, a video signaldriving circuit 201, a scanning signal driving circuit 202, a commonelectrode potential controlling circuit 203, and a synchronizing circuit204. In addition, the display unit 200 includes scanning signalelectrodes 212, a video signal electrode 211, a plurality of pixelelectrodes 214 arranged in matrix form, a plurality of switchingelements 213 which transmit video signals to the pixel electrodes 214,and common electrodes 215. The common electrode potential controllingcircuit 203 changes the potential of the common electrodes 215 into apulse shape after the scanning signal driving circuit 202 scans theentire scanning electrodes 212 and transmits video signals to the pixelelectrodes 214.

Next, an operation of the liquid crystal display apparatus according tothe first embodiment having such a configuration will be described withreference to FIG. 15 and FIG. 16. FIG. 15 is a drawing for showing anexemplary timing according to the embodiment and FIG. 16 is a drawingfor showing an exemplary waveform according to the embodiment. Accordingto the embodiment, after video signals are transmitted to the pixelelectrodes 214, the potential of the common electrode is changed into apulse shape. Through the change of the potential into the pulse shape, apotential difference between the potentials of the pixel electrodes andthe potential of the common electrode developed after the transmissionof the video signals varies between a time period 301 before thepotential is changed into a pulse shape, a time period 302 over whichthe pulse height portion to which the transmission of the video signalsvaries is formed, and a time period 303 after the change of thepotential into the pulse shape has ended. However, the potentialdifference before its change into the pulse shape may be equal to thepotential difference after its change into the pulse shape. As a result,a change in the state and the response speed of a display substance ateach time period can be adjusted. Therefore, it is possible to increasethe response speed and it is also possible to decrease it as required.The effect of the adjustment of the response speed is adjusted by adifference between the potentials changed into a pulse shape in (thetime period 301 before its change into the pulse shape, the time period302 during the formation of the pulse height portion to which thetransmission of the video signals varies, and the time period 303 afterits change into the pulse shape) and the length of the time period overwhich the potential is changed into a pulse shape.

And further, the potential difference between the potential developed inthe time period 301 before its change into the pulse shape and thepotential developed in the time period 303 after its change into thepulse shape is adjusted so as to complement the effect of a variation inthe potentials of the pixel electrodes resulting from a capacitancecoupling associated with the change into the pulse shape. Moreover, thepotential difference is adjusted according to the state of a displaywhich is desired after the change into the pulse shape and so on.

Next, a second embodiment of the present invention will be describedwith reference to FIG. 10 and FIG. 13. A liquid crystal displayapparatus according to the second embodiment has the display unit 200,the video signal driving circuit 201, the scanning signal drivingcircuit 202, a storage capacitance electrode potential controllingcircuit 205, and the synchronizing circuit 204. In addition, the displayunit 200 has the scanning signal electrodes 212, the video signalelectrodes 211, the plurality of pixel electrodes 214 arranged in matrixform, the plurality of switching elements 213 which transmit videosignals to the pixel electrodes 214, and storage capacitance electrodes216. The storage capacitance electrode potential controlling circuit 205changes the potential of the storage capacitance electrodes 216 into apulse shape after the scanning signal driving circuit 202 scans theentire scanning electrodes 212 and transmits video signals to the pixelelectrodes 214.

Next, an operation of the liquid crystal display apparatus according tothe second embodiment will be described. In this embodiment, by changingthe potential of the storage capacitance electrodes into the pulse shapeafter the transmission of the video signals to the pixel electrodes 214,the same effect as that described in the first embodiment can beobtained. However, the effect of such an adjustment made in thisembodiment is achieved by a variation in the potentials of the pixelelectrodes resulting from capacitance coupling and hence, such an effectis different from the effect of the first embodiment which is achievedby both the variation in the potential of the common electrode and thevariation in the potentials of the pixel electrodes resulting from thecapacitance coupling. That is, the effect of the second embodiment isnot brought about by a direct means, that is, the variation in thepotential of the common electrode is brought about by an indirect means,that is, the variation in the potentials of the pixel electrodesresulting from the capacitance coupling.

A third embodiment according to the present invention will be describedwith reference to FIG. 11 and FIG. 14. A liquid crystal displayapparatus according to the third embodiment has the display unit 200,the video signal driving circuit 201, the scanning signal drivingcircuit 202, the common electrode potential controlling circuit 203, thestorage capacitance electrode potential controlling circuit 205, and thesynchronizing circuit 204. In addition, the display unit 200 has thescanning signal electrodes 212, the video signal electrodes 211, theplurality of pixel electrodes 214 arranged in matrix form, the pluralityof switching elements 213 which transmit video signals to the pixelelectrodes 214, the common electrodes 215, and the storage capacitanceelectrodes 216. The common electrode potential controlling circuit 203changes the potential of the common electrodes 215 into a pulse shapeafter the scanning signal driving circuit 202 scans the entire scanningelectrodes 212 and transmits video signals to the pixel electrodes 214.The storage capacitance electrode potential controlling circuit 205changes the potential of the storage capacitance electrodes 216 into apulse shape after the scanning signal driving circuit 202 scans theentire scanning electrodes 212 and transmits video signals to the pixelelectrodes 214.

Next, an operation of the liquid crystal display apparatus according tothe third embodiment will be explained. In this embodiment, by changingthe potentials of both the common electrode and the storage capacitanceelectrode into the pulse shapes, the state of a display, a responsespeed, and so on are adjusted. Therefore, the operation of the liquidcrystal display apparatus according to the embodiment corresponds to acombination of the operation described in the first embodiment and theoperation described in the second embodiment.

However, in this embodiment, excellent operation, which cannot beachieved by such a mere combination, can be expected. For example, bymaking the polarity of the change into the pulse shape of the commonelectrode differ from that of the storage capacitance electrode, thevariation in the potential of the pixel electrode resulting from thecapacitance coupling can be suppressed. On the other hand, by making thecommon electrode and the storage capacitance electrode have the samepolarity of the change into the pulse shape, the variation can beincreased further, thereby the effect of the liquid crystal displayapparatus of the third embodiment can be doubled when compared withthose described in the first and second embodiments. And further, bymaking their timing of the synchronization different from each other orby making their length of the time period over which the change into thepulse shape is performed different from each other, the response speedcan be adjusted more minutely.

A fourth embodiment of the invention will be explained below. In thefourth embodiment, the configurations of a liquid crystal displayapparatus and a display unit correspond to those described in the firstembodiment shown in FIG. 9 and FIG. 13. That is, the liquid crystaldisplay apparatus according to the fourth embodiment also has thedisplay unit 200, the video signal driving circuit 201, the scanningsignal driving circuit 202, the common electrode potential controllingcircuit 203, and the synchronizing circuit 204. The display unit 200 hasthe scanning signal electrodes 212, the video signal electrodes 211, theplurality of pixel electrodes 214 arranged in matrix form, the pluralityof switching elements 213 which transmit video signals to the pixelelectrodes, and the plurality of common electrodes 215 which areelectrically isolated from one another. The fourth embodiment differsfrom the first embodiment in that after the scanning signal drivingcircuit 202 scans part of the scanning electrodes 212 and transmitsvideo signals to the pixel electrodes 214, the common electrodepotential controlling circuit 203 changes the potentials of the commonelectrodes 215, which correspond to the scanning electrodes 212 scannedby the scanning signal driving circuit 202, into pulse shapes.

A fifth embodiment according to the present invention will be describedbelow. In the fifth embodiment, the configurations of a liquid crystaldisplay apparatus and a display unit correspond to those described inthe second embodiment and will be explained with reference to FIG. 10and FIG. 13. The liquid crystal display apparatus according to the fifthembodiment also has the display unit 202, the video signal drivingcircuit 201, the scanning signal driving circuit 202, the storagecapacitance electrode potential controlling circuit 205, and thesynchronizing circuit 204. Also, the display unit 200 has the scanningelectrodes 212, the video signal electrodes 211, the plurality of pixelelectrodes 214 arranged in matrix form, the plurality of switchingelements 213 which transmit video signals to the pixel electrodes 214,and the plurality of storage capacitance electrodes 216 which areelectrically isolated from one another. The fifth embodiment differsfrom the second embodiment in that after the scanning signal drivingcircuit 202 scans part of the scanning electrodes 212 and transmitsvideo signals to the pixel electrodes 214, the storage capacitanceelectrode potential controlling circuit 205 changes the potentials ofthe storage capacitance electrodes 216, which correspond to the scanningelectrodes 212 scanned by the scanning signal driving circuit 202, intopulse shapes.

A sixth embodiment according to the present invention will be describedbelow. The configuration of the sixth embodiment corresponds to that ofthe third embodiment shown in FIG. 11 and FIG. 14. A liquid crystaldisplay apparatus according to the sixth embodiment also has the displayunit 200, the video signal driving circuit 201, the scanning signaldriving circuit 202, the common electrode potential controlling circuit203, the storage capacitance electrode potential controlling circuit205, and the synchronizing circuit 204. Also, the display unit 200 hasthe scanning electrodes 212, the video signal electrodes 211, theplurality of pixel electrodes 214 arranged in matrix form, the pluralityof switching elements 213 which transmit video signals to the pixelelectrodes 214, the plurality of common electrodes 215 which areelectrically isolated from one another, and the plurality of storagecapacitance electrodes 216 which are electrically isolated from oneanother. The sixth embodiment differs from the third embodiment in thatafter the scanning signal driving circuit 202 scans part of the scanningelectrodes 212 and transmits video signals to the pixel electrodes 214,the common electrode potential controlling circuit 203 changes thepotentials of the common electrodes 215, which correspond to thescanning electrodes 212 scanned by the scanning signal driving circuit202, into pulse shapes and after the scanning signal driving circuit 202scans part of the scanning electrodes 212 and transmits video signals tothe pixel electrodes 214, the storage capacitance electrode potentialcontrolling circuit 205 changes the potentials of the storagecapacitance electrodes 216, which correspond to the scanning electrodes212 scanned by the scanning signal driving circuit 202, into pulseshapes.

Next, the operations of the liquid crystal display apparatuses accordingto the fourth to sixth embodiments of the invention will be describedwith reference to FIG. 17 to FIG. 20. FIG. 17 is a drawing showing anexemplary order in which the electrodes, which are electrically isolatedin the display units described in the fourth to sixth embodiments, arescanned. FIG. 18 is a drawing for explaining an exemplary shape of theelectrodes which are electrically isolated in the display unitsdescribed in the fourth to sixth embodiments. FIG. 19 is a drawingshowing an exemplary display for a cellular phone to which the liquidcrystal display apparatuses according to the fourth to sixth embodimentsare applied. FIG. 20 is a drawing showing an exemplary arrangement ofthe electrically isolated common electrodes and the electricallyisolated storage capacitance electrodes of the display units describedin the fourth to sixth embodiments.

In the fourth to sixth embodiments of the invention, since the commonelectrodes, the storage capacitance electrodes, or both of these isdivided into a plurality of portions electrically isolated, the samechange in the potentials as those described in the first to thirdembodiments can be given to only part of the display unit. As a result,in the fourth to sixth embodiments, the effect exerted on the entiredisplay unit described in the first to third embodiments can be limitedso as to be exerted on part of the display unit. That is, since thedisplay unit is divided into a plurality of sub display units, it ispossible to give a change in potential to the individual sub displayunits in sequence while scanning the sub display units in sequence.Moreover, it is also possible to simultaneously give a change inpotential to the plurality of sub display units. In either case, thelocations of the sub display units scanned in sequence within thedisplay unit can be selected freely. For example, it is possible to givea change in potential in order shown by the numbers of FIG. 17. That is,it is possible to give a change in potential in such a way that not onlyare the suitably selected regions scanned in sequence but the pluralityof regions are simultaneously changed at the scanning order of No. 3 andNo. 5. Furthermore, for example, it is possible to give the changethrough the use of different areas and shapes shown in FIG. 18.

Furthermore, it is also possible to selectively give a change inpotential only to part of the entire display unit among all displayunits. As a result, it is possible to make a difference between thestate of display at the selected display unit and the state of displayat the nonselected display unit. For example, it is possible to producea fast response at the portion of a display region A of the display forthe cellular phone shown in FIG. 19, while it is possible to produce aresponse at normal speed at the portion of a display region B. As aconsequence, for example, a display is divided into a portion where fastmoving image displays such as TV images are required and a portion wherefreeze-frame picture-like displays, on which images are not changed somuch, are required, so that it becomes possible to reduce powerconsumption as a whole.

On the other hand, in the sixth embodiment of the invention, by making adifference between the shape of the electrically isolated commonelectrodes and the shape of the electrically isolated storagecapacitance electrodes as shown in FIG. 20, the display unit is dividedinto four regions, that is, the region where only the potentials of thecommon electrodes are changed into pulse shapes, the region where onlythe potentials of the storage capacitance electrodes are changed into apulse shape, the region where the potentials of both the commonelectrodes and the storage capacitance electrodes are changed into pulseshapes, and the region where the change into pulse shapes are not made.

By these operations, for example, a response at a certain region where aresponse speed is particularly slow in the display unit can be sped up.Further, it is possible to correct the unevenness of brightnessresulting from viewing angle dependence by adjusting a response speed ofthe display unit so as to correct viewing angle dependency whichdevelops within the display unit. Still further, it is possible tocorrect differences in the unevenness of display and flicker which aredeveloped according to the scanning order of scanning lines and whichare affected by the positions of the display within the screen. That is,by limiting regions where the change into the pulse shape is made in acertain time period to some regions, the unevenness of display andflicker at the other regions can be suppressed or the unevenness ofdisplay and flicker at the regions where the change into the pulse shapeis made can be suppressed. The common electrodes and the storagecapacitance electrodes, which are separately provided to this pluralityof regions, can also be, for example, synchronized with the scanningtiming of the scanning line at a certain relationship for scanning. As aconsequence, the unevenness of display and flicker resulting from thescanning can be suppressed efficiently.

A liquid crystal display apparatus according to a seventh embodiment ofthe invention corresponds to that described in the first, third, fourth,or sixth embodiment in which the potential of the common electrode 215to be changed into a pulse shape is equal to the potential by whichdisplay produced by the display unit 200 is not reset.

A liquid crystal display apparatus according to an eighth embodiment ofthe invention corresponds to that described in the second, third, fifth,or sixth embodiment in which the potential of the storage capacitanceelectrode 216 to be changed into a pulse shape is equal to the potentialby which display produced by the display unit 200 is not reset.

In the seventh and eighth embodiments, since the potential to be changedinto a pulse shape is equal to the potential by which a display producedby the display unit is not reset, the foregoing delay is not developedand responses are sped up. The explanation of the principle of theforegoing will not be repeated because it has been made in the item“Means for Solving the Problems,” but an example of the actualfabrication of the liquid crystal display apparatus according to theseventh embodiment will be described below based on its operation andeffect in comparison with a comparative example.

The example of the seventh embodiment will be explained in comparisonwith the comparative example in which a voltage to be reset is applied.In the example and the comparative example, a thin film transistor madeof amorphous silicon to be described below is used as the switchingelement, and a nematic liquid crystal substance is used as the displaysubstance of the display unit to produce a twisted nematic alignment.

FIG. 21 is a graph for explaining a variation in transmittance withrespect to time indicated in a case where a change into a pulse shapefor reset is provided as in the case with conventional reset driving. Onthe other hand, FIG. 22 is a graph for explaining a variation intransmittance with respect to time indicated in a case where a changeinto a pulse shape is not reset according to the present invention isprovided. To compare effects of reset states on response speeds, thesame sequence for driving is used and a change into a pulse shape isgiven to both of these. That is, video signals are initially written toall pixels and then a change into a pulse shape (a reset state isprovided in FIG. 21 and the reset is not carried out in FIG. 22) isgiven. When the same change into the pulse shape as that of theconventional reset as shown in FIG. 21, the first delay, which is shownin the item “Means for Solving the Problems,” develops and then, thesecond delay develops after the change into the pulse shape ends. Incontrast, in the change into the pulse shape according to the presentinvention shown in FIG. 22, neither the first delay nor the second delaydevelop and after the change into the pulse shape ends, a response isproduced immediately so as to exhibit a desired transmittance. As aresult, in the conventional reset state, a desired transmittance(indicated by an alternate long and two short dashed lines in FIG. 21)is not reached. On the other hand, in the change into the pulse shapeaccording to the present invention, the maximum transmittance which isable to be secured at the conventional reset state (indicated by a chainline in FIG. 21) is reached immediately after the change into the pulseshape ends, following which the desired transmittance is reached,thereby the transmittance is stabilized.

Next, a ninth embodiment according to the present invention will bedescribed below. A liquid crystal display apparatus according to theninth embodiment corresponds to that described in the first, third,fourth, sixth, or seventh embodiment in which the potential of thecommon electrodes 215 vary between at least three potentials andpreferably between at least four potentials.

A liquid crystal display apparatus according to the tenth embodiment ofthe invention corresponds to that described in the second, third, fifth,sixth, or eighth embodiment in which the potential of the storagecapacitance electrodes 216 vary between at least three potentials andpreferably at least four potentials.

Next, the operation of the liquid crystal display apparatuses accordingto the ninth and tenth embodiments will be explained with reference toFIG. 16. In these embodiments as well, by giving a voltage change shownin FIG. 16, a change into a pulse shape can be effectively given to boththe polarities of video signals whose polarity is reversed.

Next, an eleventh embodiment according to the present invention will beexplained below. A liquid crystal display apparatus according to theeleventh embodiment corresponds to those described in the first to tenthembodiments in which the potential of the common electrodes 215 or thestorage capacitance electrodes 216 are changed into a pulse shape so asto temporarily increase a potential difference between the potential ofthe pixel electrodes 214 and the potential of the common electrodes 215or the potential of the storage capacitance electrodes 216.

Next, the operation of the liquid crystal display apparatus according tothe eleventh embodiment of the invention will be explained. In theeleventh embodiment, by temporarily increasing such a potentialdifference, an overdrive (feed-forward) effect can be obtained withoutthe control of video signals. In this invention, unlike conventionaloverdriving in which video signals are controlled, it is possible tosimultaneously produce the overdrive effect on the entire regionelectrically connected.

Next, a twelfth embodiment according to the present invention will beexplained. A liquid crystal display apparatus according to the twelfthembodiment corresponds to those described in the first to eleventhembodiments in which the potential of the video signals is differentfrom the potential of a video signals which is in a stable display statein static driving in consideration of the response characteristics ofthe display unit 200 during charge holding type driving. For example, byproviding overshoot characteristics, arrival time for a predeterminedtransmittance is shortened.

In this embodiment, to transmit video signals to the pixel electrodes214 via the switching elements, charge holding type driving, in whichthe display apparatus is driven so as to hold a charge at the instantwhen the switching elements are turned off, is adopted instead of staticdriving in which the display unit is driven by continuing to applyvoltage.

Next, a thirteenth embodiment according to the present invention will beexplained. A liquid crystal display apparatus according to thethirteenth embodiment corresponds to that described in the twelfthembodiment in which the potential of the video signals is determined bycomparing the hold data of the individual pixels before the writing ofthe video signals and display data to be newly displayed inconsideration of the response characteristics of the display unit 200.Specifically, by using a comparison computing unit and a look-up table(LUT), a video signal, by which a desired display state can be obtained,is determined. In particular, the video signal is determined bycomparing the hold data of the individual pixels before the writing ofthe video signal, a variation in the potentials of the pixel electrodesassociated with a variation in the potentials of the common electrodesto be changed into a pulse shape, the potentials of the storagecapacitance electrodes 216 to be changed into a pulse shape, or thepotentials of both of these, and display data to be newly displayed. Thevariation in the potentials of the common electrodes includes thevariation in the potentials of the pixel electrodes caused duringpolarity reversal which is brought about when driving is performed byreversing the polarity of the potentials of the common electrodes, thepotentials of the storage capacitance electrodes, or the potentials ofboth of these. Furthermore, the data to be newly displayed is alsodetermined in consideration of the polarity reversal of data signals,that is, the variation in the potentials of the pixel electrodesresulting from capacitance coupling associated with the switching of theframes and so on. Through the waveform application taking into accountsuch a variation, variations in gradation and flicker do not occur.

The operation of some of the liquid crystal display apparatus accordingto the embodiments performed by using a special method will bespecifically explained with reference to FIG. 6 and FIG. 7. FIG. 6 is adrawing for explaining a relationship between wiring electricallyconnected to a certain pixel and potentials. Video signal data iswritten into a liquid crystal capacitor 501 and a storage capacitor 502via a pixel TFT 503. A potential at a node through which writing iscarried out is represented as a pixel potential VLC (507). A potentialof an opposing electrode of the liquid crystal capacitor, that is, anopposing electrode potential VCOM (506) is supplied from an externalpower source and between an external electrode and the opposingelectrode, additional resistance and additional capacitance are present.A portion where a time constant is determined by the additionalresistance and the additional capacitance is indicated in FIG. 6 as thetime constant circuit 504 of the opposing electrode. Likewise, apotential on the side other than the liquid crystal side of the storagecapacitor, i.e., a storage capacity potential VST (508) is supplied froman external power source and the time constant circuit 505 of thestorage capacity line is present as well. When consideration is given tothese time constants, it is found that the potentials vary complexly.Those complex variations are shown in FIG. 7. FIG. 7 shows variationsdVLC in the individual potentials shown in FIG. 6, i.e., the opposingelectrode potential VCOM (506), the storage capacity line potential VST(508), and the pixel potential VLC (507) with respect to time. Theopposing electrode is often made of a transparent electrode in generaland its wiring resistance is relatively high. Therefore the timeconstant of the wiring, that is, the response time of the variations inthe potentials is, for example, 130 microseconds. When an initialpotential (which is represented as 0V in FIG. 7) stands for 0%, the term“response time” refers to a time period during which 90% of a differencebetween a target potential (5V in FIG. 7) and the initial potential isreached. On the other hand, the storage capacitance electrode line ismade of a metal and is of high wiring resistance. Therefore the timeconstant of the storage capacity line potential is, for example, 8microseconds. Even when the voltages at the opposing electrode and thestorage capacitance electrode line are varied by the same voltage (forexample, from 0V to 5V as shown in FIG. 7) with the same timing, thevariation in the pixel electrode potential dVLC develops through adifference between the time constant of the opposing electrode potentialand the time constant of the storage capacity line potential. Such avariation in the pixel electrode potential develops a difference indisplay and the difference is recognized as flicker.

Furthermore, voltage fluctuation is developed by capacitance couplingvia parasitic capacities between not only the gate and the source of thepixel TFT 503 but also the gate and the drains of the pixel TFT 503.Moreover, voltage fluctuation is developed by the leakage current of thepixel TFT 503 as well. In particular, these voltage fluctuations aredeveloped when the frames are changed, that is, when signals areinverted at each frame. By taking into account these voltagefluctuations as well, the unevenness of display and flicker can bereduced.

In this embodiment, hold data roughly corresponds to the sum of chargesheld between the pixel electrodes 214 and the common electrodes 215 andcharges held between the pixel electrodes 214 and the storagecapacitance electrodes 216. Also, display data to be newly displayedroughly corresponds to the average of the sum of charges between thepixel electrodes 214 and the common electrodes 215 and charges betweenthe pixel electrodes 214 and the storage capacitance electrodes 216within display time or the sum of charges between the pixel electrodes214 and the common electrodes 215 and charges between the pixelelectrodes 214 and the storage capacitance electrodes 216 at the timewhen the display time has ended.

In the twelfth embodiment of the invention, by providing a chargedifferent from that of static driving, a potential which is suitable fordriving using the pixel switches can be applied. And further, byproviding overshoot characteristics to video signals, a fast responsespeed attributed to the overdrive effect can be achieved.

Moreover, by comparing hold data of the individual pixels before thewriting of the video signals and display data to be newly displayed,more efficient video signals can be selected. For example, a circuitdescribed in Japanese Patent No. 3039506 can be used. FIG. 23 shows anexample of a driving unit described in this patent publication. Thisdisplay apparatus displays images of individual display frames byfeeding writing signal voltages, which correspond to display data, toindividual pixels designated in sequence. A driving unit 80, whichdrives a liquid crystal display 64, is connected between a signal source65 and a liquid crystal display (LCD) 64. The driving unit 80 has ananalog-digital converter circuit (hereinafter abbreviated as ADCcircuit) 66 connected to the signal source 65, a first latch circuit 69connected to the ADC circuit 66, and an output controlling buffer 68connected to the ADC circuit 66. The driving unit 80 further has amemory 71 connected to the output controlling buffer 68, a second latchcircuit 70 connected to the memory 71 via a node which connects theoutput controlling buffer 68 and the memory 71, a computing element 72connected to the first latch circuit 69 and the second latch circuit 70,and a timing controlling circuit 67. The ADC circuit 66 is synchronizedwith a clock ADCLK and converts an analog signal supplied by the signalsource 65 to a digital signal. The output controlling buffer 68, whichhas an output controlling function, receives a control signal OE tobring an output terminal into a high impedance (hereinafter “Hi-Z”)state. Here, at an output enable state in which inputted data isoutputted when the control signal OE is at a high level, the outputterminal becomes Hi-Z when the signal is at a low level. The memory 71has a capacity for one full frame or more and is controlled by anaddress signal ADR and a control signal R/W. The memory 71 performsreading operation when R/W is at a high level and the memory 71 performswriting operation when R/W is at a low level. The first and second latchcircuits 69 and 70 are each a circuit which captures input data andholds them while receiving a clock LACLK. In this case, the first andsecond latch circuits 69 and 70 capture data on a clock rising edge andholds them until the next rising edge. The first latch circuit 69latches a video signal voltage VS (m, n) and the second latch circuit 70latches a video signal voltage VS (m, n−1). A writing signal voltage Vex(m, n) at the mth pixel of the frame n is determined from the linear sumVex(m,n)=AVS(m, n)+BVS(m, n−1) (A and B are constants)of a video signalvoltage VS (m, n−1) at the mth pixel of the frame n−1 displayed the lasttime and a video signal voltage VS (m, n) at the mth pixel of the framen to be displayed next time. Then the computing element 72 sets awriting signal voltage Vex (m, n) at the mth pixel of the frame naccording to the linear sum of the video signal voltage VS (m, n−1) atthe mth pixel of the display frame n−1 displayed the last time and thevideo signal voltage VS (m, n) at the mth pixel of the frame n to bedisplayed next time according to the expression Vex(m, n)=AVS(m,n)+BVS(m, n−1). The timing control circuit 67 controls the timing ofeach signal. In addition, the memory 71 and the computing element 72constitute a display controlling unit.

However, in the present invention, since the response speed is increasedby the change in the pulse shape of the common electrode potential andso on, a voltage added at the time of providing the overdrive effect canbe set at a smaller value when compared with that of the conventionaloverdrive system. In the conventional overdrive is high, since a voltageapplied during the overdrive, the alignment state of the liquid crystalis often brought to a reset state, which causes, for example, a responsespeed required to return to a white image to become slow. In the presentinvention, since a voltage applied during the overdrive is low, thealignment state of the liquid crystal is not brought to the reset state.

Next, a fourteenth embodiment of the invention will be described below.A liquid crystal display apparatus according to the fourteenthembodiment corresponds to those described in the first to thirteenthembodiment in which a field response type substance is interposedbetween the pixel electrodes 214 and the common electrodes 215 of thedisplay unit 200. Moreover, it is preferable that the field responsetype substance of the display unit be made of a liquid crystalsubstance.

The pixel electrodes 214 and the common electrodes 215 may be providedon different substrates, respectively, may be provided on the samesubstrate, and may be provided between substrates.

By using the field response type substance, the response state of thesubstance can be changed according to the potential changed into a pulseshape. In particular, through the use of a liquid crystal substance, thealignment and the response speed of the liquid crystal substance changeaccording to the potential changed into a pulse shape.

Next, a fifteenth embodiment of the invention will be described below.The liquid crystal display apparatus according to the fifteenthembodiment corresponds to that described in the fourteenth embodiment inwhich the liquid crystal substance is a nematic liquid crystal and hastwisted nematic alignment. It is preferable that between the twist pitchp (μm) of the liquid crystal substance having the twisted nematicalignment and the average thickness d (μm) of the liquid crystalsubstance layer having the twisted nematic alignment, a relationshipp/d<20 be established. It is preferable that a relationship p/d<8 beestablished between the twist pitch p (μm) of the liquid crystalsubstance having the twisted nematic alignment and the average thicknessd (μm) of the liquid crystal substance layer having the twisted nematicalignment.

In the liquid crystal display apparatus according to the fifteenthembodiment, to implement a wide viewing angle, an optical compensationplate is provided as necessary. It is preferable that the opticalcompensation plate compensates optical characteristics in apredetermined state of the liquid crystal substance. For example, theoptical compensation plate is formed so as to compensate opticalcharacteristics which can be secured from the alignment structure of theliquid crystal substance during the application of voltage.

By employing the twisted nematic liquid crystal, a continuous change inthe gradation can be obtained. In particular, through the presence ofsuch a relationship between the twist pitch p and the thickness d, itbecomes possible to increase the torque required for the nematic liquidcrystal to return to a twisted state. As a result, it becomes possibleto increase a response speed at the time of returning to the state inwhich no voltage is applied or a low voltage is applied. That is, thefall response can be sped up.

Next, the effect of the fifteenth embodiment will be explained by usingan example. When a normally white image can be obtained by preparingliquid crystals different in twist pitch, by fabricating liquid crystalpanels for the respective liquid crystals, and by arranging a pair ofpolarizing plates outside the panels, the effect of the embodiment isconfirmed. The gap of substrates (the thickness of the liquid crystallayer) was set to 2 μm and the liquid crystals having twist pitches of 6μm, 20 μm, and 60 μm were used. The thickness of the liquid crystal actson the response speed with the square of the thickness. For example,when the slimness of the liquid crystal layer is set at 6 μm (triplethickness), the response speed is decreased to a ninth. Because of this,the thickness of the liquid crystal layer is preferably 4 μm or less andmore preferably 3 μm or less. Although there is no limitation to thesmall thickness of the liquid crystal layer, in consideration of thelimitation on the twist pitch of the liquid crystal and of difficulty inthe production of the gap of the substrates, the thickness of the liquidcrystal layer is preferably 0.5 μm or more and more preferably 1 μm ormore. In such a state, the time-transmittance characteristics of theliquid crystals at the time of a rise (optical responses during the fallof the liquid crystals, that is, responses from a dark state to a brightstate in the normally white arrangement) were observed. By bringingblack image states to white image states in which complete transmissionis developed, the gradients of changes in transmittance close to 50% wasdetermined from time-transmittance characteristics observed. The reasonwhy a transmittance close to 50% was selected is that the change in thetransmittance shows a maximum value around 50%. FIG. 24 is a graph inwhich a relationship between the determined gradient (%/ms: verticalaxis) and the ratio of the twist pitch/the thickness of the liquidcrystal layer (p/d: horizontal axis) is plotted. Here, it is a matter ofcourse that the thickness of the liquid crystal layers is equivalent tothe distance of the gaps between the substrates. It is found from FIG.24 that when the ratio of the twist pitch/the thickness of the liquidcrystal layer becomes small, the gradient becomes large and hence, theresponse during the rise of the liquid crystal is sped up. Inparticular, an abrupt increase in the gradient is found from the ratioof about 15 and when the ratio become about 3, the gradient exceeds 50(%/ms). That is, ideally, it becomes possible to achieve a responsewithin 2 milliseconds as well. In FIG. 24, when the ratio p/d of 30 iscompared with the ratio p/d of 3, a gradient at the ratio p/d of 3 canbe roughly doubled, thereby it is found that there is a possibility thatthe optical response time during the fall of the liquid crystal can behalved. Moreover, even under the conditions of the ratios p/d of 30 and10, the response speed is increased by 15%. In short this effect isachieved by increasing a torque required to return to a initialalignment state in which no voltage and so on is applied (that is, aroughly evenly twisted alignment state between the substrates).

Next, a sixteenth embodiment of the invention will be described below. Aliquid crystal display apparatus according to the sixteenth embodimentcorresponds to the fourteenth embodiment in which the liquid crystalsubstance having the twisted nematic alignment is stabilized by apolymer having a structure twisted roughly continuously. Moreover, it ispreferable that the liquid crystal substance be stabilized by a polymerstructure effected during the application of no voltage or of a lowvoltage.

Moreover, it is preferable that the substance be stabilized by a polymerby adding a photocurable monomer into the twisted nematic liquid crystaland by giving light irradiation. It is further preferable that thephotocurable monomer be a liquid crystal monomer having a liquid crystalskeleton. And it is further preferable that the liquid crystal monomerbe a diacrylate or a monoacrylate made by combining polymeric functionalgroups and the liquid crystal skeleton without a methylen spacer.

Next, the operation of the liquid crystal display apparatus according tothe sixteenth embodiment of the invention will be described below byusing an example. A twisted nematic liquid, to which 2% of aphotocurable diacrylate liquid crystal monomer having a structuralformula shown in Chemical Formula 1 described below was added, wasinjected and then the liquid crystal was polymerized by providing lightirradiation (ultraviolet light: 1 mW/cm²×600 sec) in the state of theapplication of no voltage to give a TN type display apparatus having anormally white image. In contrast to such a process, when a twistednematic liquid crystal, to which 2% of a photocurable monoacrylateliquid crystal monomer made by combining polymeric functional groupshaving a structure shown in Chemical Formula 2 described below and theliquid crystal skeleton without a methylene spacer, was injected andthen the liquid crystal was polymerized by providing light irradiationin the state of application of no voltage, the same effect as that ofuse of the diacrylate liquid crystal monomer was achieved.

This is because use of the monomer not involving a methylene spacerreceives less limitation of responsiveness against voltage of the liquidcrystal with respect to the addition of the monomer. As a matter ofcourse, liquid crystal monomers other than those monomers can be used byadjusting the amount of the monomer added. To stabilize the alignmentproperties of the liquid crystal to the unevenness of the substrate, theamount of the monomer added can be 0.5% or more to the liquid crystaland it is preferable that the amount be 1% or more. When theresponsiveness of the liquid crystal is 5% or less, the inhibition ofresponsiveness does not occur, while the responsiveness of 3% or less ispreferable.

As described above, by performing polymer stabilization, the same effectas that described in the fifteenth embodiment can be obtained. This isbecause a torque, which is required to return to a state in which thepolymer stabilization has been established, increases.

Next, a seventeenth embodiment of the invention will be described below.The embodiment is the liquid crystal display apparatus according to thefourteenth embodiment in which the liquid crystal substance is in anelectrically controlled birefringence mode.

Furthermore, in the fourteenth embodiment, the liquid crystal substancecan have a pie-type alignment (bend-type alignment). In addition, it ispreferable that a liquid crystal display apparatus having the pie-typealignment be provided with an optical compensation plate and have an OCB(optically compensated birefringence) mode.

Moreover, in the fourteenth embodiment, the liquid crystal substance canbe in a VA (vertical alignment) mode in which homeotropic alignmentdevelops. It is preferable that a wide viewing angle be implemented byproviding multidomains. As a method for providing multidomains, a MVA(multidomain vertical alignment) method, a PVA (patterned verticalalignment) method, an ASV (advanced super V) method, and so on can beused. In addition, it is further preferable that a wider viewing anglecan be implemented by providing an optical compensation plate on an asneeded basis.

And further, in the fourteenth embodiment, an IPS (in-plane switching)mode can be used in which the liquid crystal substance responds throughan electric field which develops parallel to the substrate surface. Theresponsiveness can be preferably further improved by providing aSuper-IPS mode using electrodes having a zigzag structure.

Still further, in the fourteenth embodiment, the liquid crystalsubstance may be in a FFS (fringe field switching) mode or an AFFS(advanced fringe field) mode.

Moreover, in the fourteenth embodiment, as the liquid crystal substance,it is possible to use a ferroelectric liquid crystal substance, anantiferroelectric liquid crystal substance, or a liquid crystalsubstance exhibiting an electroclinic type response. It is preferablethat the liquid crystal substance has the transmittance response to thevoltage which is a V-shaped response or a half V-shaped response.

Furthermore, in the fourteenth embodiment, the liquid crystal substancemay be a cholesteric liquid crystal substance.

Next, an eighteenth embodiment of the invention will be described below.The embodiment is the liquid crystal display apparatus according to theseventeenth embodiment in which the alignment of the liquid crystalsubstance is stabilized in such a way that the substance is produced asa polymer having a structure in the state of the application of novoltage or of a low voltage.

It is preferable that the liquid crystal substance be polymerized byadding a photocurable monomer to the twisted nematic liquid crystal andby irradiating the liquid crystal with light.

It is further preferable that the photocurable monomer be a liquidcrystal monomer having a liquid crystal skeleton.

It is still further preferable that the liquid crystal monomer is adiacrylate or a monoacrylate made by combining polymeric functionalgroups and a liquid crystal skeleton without the use of a methylenespacer.

In the seventeenth and eighteenth embodiments of the invention, liquidcrystal modes other than the twisted nematic liquid crystal are used.

The pie-type mode and the OCB mode are modes capable of exhibiting botha high-speed response and a wide viewing angle. By applying theinvention, a rise response can be further sped up.

A line of the VA mode exhibits both a wide viewing angle and ahigh-speed response other than an intermediate gradation response. Byapplying the invention, a high-speed response including the intermediategradation response can be achieved.

The IPS mode has a wide viewing angle. Although its rise response isslower than that of the VA mode, its intermediate gradation response isfaster than that of the VA mode. However, by applying the invention, ahigh-speed response including a rise response can be implemented. TheFFS mode has a wide viewing angle and shows response characteristicswhich are similar to those of the IPS mode. By applying the invention,high-speed response including rise response can be implemented.

Ferroelectric liquid crystals, antiferroelectric liquid crystals,electroclinic liquid crystals, and so on have an extremely high-speedresponse and a wide viewing angle. Even when these liquid crystals areused, high-speed responses can be achieved by applying the invention. Onthe other hand, it is also possible to slow the responses.

On cholesteric liquid crystals as well, the present invention actseffectively.

As for the fall responses of these liquid crystal modes, their responsescannot be sped up by the adjustment of the twist pitch as in the casewith the twisted nematic type. Therefore, these polymers are stabilizedin the state of the application of no voltage.

In the display apparatus according to the present invention, the displaysubstance and the display mode are not limited to the several kindsdescribed in the above-mentioned embodiments. That is, as long as thesubstance is an electric field response substance so that the behaviorof the response depends on the electric field strength, the period ofapplication, the magnitude relationship with the threshold value, andthe like, the invention is effective for any of such substances.

Next, a nineteenth embodiment according to the present invention is acolor liquid crystal display apparatus according to the first througheighteenth embodiments described above, in which a color filter is usedin the display unit so that color display is achieved.

The invention permits the speedup of the response time of the liquidcrystal display apparatus using a color filter. Thus, a liquid crystaldisplay apparatus suitable for moving image displays and the like isobtained.

Next, a twentieth embodiment according to the present invention is astereoscopic display liquid crystal display apparatus according to thefirst through eighteenth embodiments described above, in which adouble-sided prism sheet shown in FIG. 26 or a lenticular lens sheet(lenticular film) shown in FIG. 25 is used so that stereoscopic displayis achieved. Preferably, a time-sharing type stereoscopic display methodis used in which a scanning backlight is formed by projecting light intoa backlight alternately in time from two positions and in which insynchronization with this, the video signal is switched into the videosignal for the right eye and the video signal for the left eyealternately in time at twice or more the ordinary frequency so thatstereoscopic display is achieved.

Next, an operation of the twentieth embodiment of the invention will beexplained below with reference to FIG. 25 and FIG. 26. A lenticular lens(lenticular film) 121 shown in FIG. 25 comprises a plurality ofcylindrical lenses 122. This allows the image for the right eye and theimage for the left eye to be distributed to the respective eyes byutilizing the positional relationship with the pixels. Further, adouble-sided prism sheet shown in FIG. 26 is provided with lenticularlenses 123 similar to those of FIG. 25 on one side and with lightseparating prisms 124 on the other side. By virtue of this, thedouble-sided prism sheet shown in FIG. 26 can separate the light at alarger angle in comparison with the simple lenticular lens shown in FIG.25. In the scanning backlight, for example, light sources are arrangedon the right and left of the light guide plate for the backlight. One ofthe light sources is used as the light source for the left eye, whilethe other is used as the light source for the right eye. When the imagefor the left eye or the image for the right eye to be displayed on thedisplay unit is selected in synchronization with the light source to beturned ON, stereoscopic display is achieved. For example, the imagesneed to be switched at a frequency of 120 Hz or higher. Thus, thespeedup realized by the invention acts remarkably effectively.

In the invention, even when the lenticular lens is used or the scanningbacklight is used, no difference arises in the number of pixels whentwo-dimensional display and three-dimensional display are switched foreach other. Further, when the scanning backlight is used, the inside ofthe pixel is not divided into two. Thus, a high resolution or a highnumerical aperture is easily realized.

Next, a twenty-first embodiment according to the present invention willbe explained below. This embodiment is a color field sequential (colortime-sharing) type liquid crystal display apparatus according to thefirst through eighteenth embodiments described above, in which the videosignal is divided into a plurality of color video signals correspondingto a plurality of colors and in which light sources corresponding to aplurality of colors are used so that a plurality of color video signalsare displayed sequentially in time in synchronization with a pluralityof color video signals at a predetermined phase difference.

The twenty-first embodiment according to the present invention realizesa color field sequential driving type display apparatus. FIG. 27 is ablock diagram showing an example of an outline of a field sequentialdisplay system. Ordinary image data is processed by a controller IC 103comprising a controller 105, a pulse generator 104, and a high-speedframe memory 106, and thereby converted into image data of each color ofred, blue, and green. The image data is inputted to a liquid crystaldisplay panel (LCD) 100 via a DAC 102. A scanning circuit in the LCD 100is controlled with driving pulses from the pulse generator of thecontroller IC. Further, an LED 101 of three colors is used as the lightsource. This LED is controlled with LED control signals 108 from thecontroller IC.

In this configuration, the image of each color needs to be switched at afrequency of 180 Hz or higher. Thus, the speedup realized by theinvention acts effectively. Further, in the case of displaying at 180Hz, the phenomenon of “color breakup” occurs in which the images ofdistinct colors separate from each other and are visible to the eyeswhen the line of sight is moved rapidly in the case of eye blinking andthe like. In order to avoid this, various approaches are taken. Forexample, white is added to the three colors of red, blue, and green.Alternatively, one particular color is repeated twice like red, green,blue, and green. Yet alternatively, driving is performed at a yetdoubled frequency (for example, 360 Hz or higher). As such, in manycases, a higher frequency is necessary in order to resolve the colorbreakup. Thus, the speedup realized by the invention acts effectively toa remarkable extent.

In the invention, the inside of the pixel is not divided into three likein a color filter method. Thus, a high resolution or a high numericalaperture is easily realized.

Next, a twenty-second embodiment according to the present invention willbe explained below. This embodiment is a liquid crystal displayapparatus of a color field sequential (color time-sharing) typetime-sharing stereoscopic display method according to the twenty-firstembodiment, in which: the video signal is composed of a video signal forthe right eye and a video signal for the left eye; the video signal forone eye is divided into a plurality of color video signals correspondingto a plurality of colors; the video signal for one eye is displayedsequentially in time in such a manner that light sources correspondingto a plurality of colors arranged at two positions are synchronized withthe video signal for one eye at a predetermined phase difference and ina manner synchronized with a plurality of color video signals; and thevideo signal for one eye is displayed sequentially in time as aplurality of divided color video signals.

In the twenty-second embodiment according to the present invention,performed simultaneously are the color field sequential displayaccording to the twenty-first embodiment and the field sequentialstereoscopic display according to the twentieth embodiment. For thispurpose, the image is switched preferably at a frequency of at least 360Hz or higher. The speedup realized by the present invention actseffectively to obtain a satisfactory response at this frequency.

In the invention, even when two-dimensional display andthree-dimensional display are switched for each other, no differencearises in the number of pixels. Further, the inside of the pixel is notdivided into six for the three dimensions and the color filters. Thus, ahigh resolution or a high numerical aperture is realized remarkablyeasily. That is, in comparison with the case that the pixel is dividedspatially, 6 times the area efficiency is obtained. This realizes astereoscopic display apparatus that provides remarkably high presence.Further, the number of wirings is reduced to ⅙. This permits theincreasing of the wiring thickness, and hence reduces the delay in thewiring.

Further, in the twenty-second embodiment, performed are the color fieldsequential display according to the twenty-first embodiment and thestereoscopic display employing the cylindrical lens of FIG. 25 or FIG.26 according to the twentieth embodiment. This can be implemented at afrequency of 180 Hz. In these embodiments, the stereoscopic displaymethod and the color field sequential display method are usedsimultaneously. Thus, the number of pixels can be reduced in comparisonwith the color filter method. This is a feature of the color fieldsequential display. Accordingly, the amount of arrangement of the signalwiring is reduced similarly. The reduction in the amount of arrangementof the signal wiring permits the reduction of the frame portion of thedisplay panel.

Next, a twenty-third embodiment according to the present invention willbe explained below. This embodiment is a display apparatus according tothe first through twenty-second embodiments described above, in whichthe pixel switch is composed of a thin-film transistor made of amorphoussilicon.

Further, this embodiment is a display apparatus according to the firstthrough twenty-second embodiments described above, in which the pixelswitch is composed of a thin-film transistor made of polycrystallinesilicon. Further, the thin-film transistor made of polycrystallinesilicon may be fabricated sequentially on a substrate, or alternativelymay be fabricated temporarily on a substrate and then transferred ontoanother substrate.

Furthermore, this embodiment is a display apparatus according to thefirst through twenty-second embodiments described above, in which thepixel switch is composed of a transistor made of single-crystallinesilicon. The transistor made of single-crystalline silicon may befabricated by a bulk silicon technique, an SOI (silicon-on-insulator)technique, an amorphous silicon technique where the channel region issingle-crystallized by means of a crystallization technique, and thelike. Further, the transistor made of single-crystalline silicon may befabricated sequentially on a substrate, or alternatively may befabricated temporarily on a substrate and then transferred onto anothersubstrate.

Furthermore, this embodiment is a display apparatus according to thefirst through twenty-second embodiments described above, in which thepixel switch is composed of an MIM (metal-insulator-metal) element.

Next, a twenty-fourth embodiment according to the present invention willbe explained below. This embodiment is a display apparatus according tothe first through twenty-third embodiments, in which the polarity of thevideo signal is reversed at a predetermined timing and in which one ortwo potentials having a longer period of application than otherpotentials among the common electrode potentials varying over aplurality of potentials are approximately equal to the intermediatepotential of the maximum potential and the minimum potential among allthe potentials applied as the video signal.

In the liquid crystal display apparatus according to the twenty-fourthembodiment of the invention, for example, waveforms shown in FIG. 28 areapplied. When the voltage change as shown in FIG. 28 is applied, theresponse speed can be increased in the period of pulse shape change.Further, the video signal is reversed relative to the common electrodepotential, so that the minimum values in the two polarities areapproximately equal to each other.

Next, a twenty-fifth embodiment according to the present invention willbe explained below. This embodiment is a display apparatus according tothe first through twenty-third embodiments, in which the polarity of thevideo signal is reversed at a predetermined timing and in which one ortwo potentials having a longer period of application than otherpotentials among the common electrode potentials varying over aplurality of potentials are approximately equal to one of the maximumpotential and the minimum potential among all the potentials applicableas the video signal.

In the liquid crystal display apparatus of this embodiment, for example,waveforms as shown in FIG. 29 are applied. When the voltage change asshown in FIG. 29 is applied, the response speed can be increased in theperiod of pulse shape change. Further, the video signal is reversedrelative to the common electrode potential, so that the maximum value ofone of the polarities is approximately equal to the minimum value of theother polarity.

Next, a twenty-sixth embodiment according to the present invention willbe explained below. This embodiment is a liquid crystal displayapparatus according to the first through twenty-third embodiments, inwhich the common electrode potential immediately before the scanningsignal driving circuit 202 begins to scan the first scanning electrodeof the scanning electrodes 212 is equal to the common electrodepotential immediately after the scanning signal driving circuit 202 hasscanned the entire scanning electrodes 212 and then transmitted a videosignal to the pixel electrodes 214 before the pulse shape change isperformed.

An example of the waveforms according to the twenty-sixth embodiment issimilar to FIG. 28.

Next, a twenty-seventh embodiment according to the present inventionwill be explained below. This embodiment is an apparatus according tothe first through twenty-third embodiments, in which the commonelectrode potential immediately before the scanning signal drivingcircuit 202 begins to scan the first scanning electrode of the scanningelectrodes 212 is different from the common electrode potentialimmediately after the scanning signal driving circuit 202 has scannedthe entire scanning electrodes 212 and then transmitted a video signalto the pixel electrodes 214 before the pulse shape change is performed.

In this configuration, preferably, the common electrode potential beforethe scanning signal driving circuit 202 begins to scan the firstscanning electrode of the scanning electrodes 212 is approximately equalto one of the maximum voltage and the minimum voltage allowed in thevideo signal to be applied from now on. Further, the common electrodepotential immediately after the scanning signal driving circuit 202 hasscanned the entire scanning electrodes 212 and then transmitted a videosignal to the pixel electrodes 214 before the pulse shape change isperformed is approximately equal to the other of the maximum voltage andthe minimum voltage allowed in the video signal having been applied.

An example of the waveforms according to the twenty-seventh embodimentis similar to FIG. 29.

Next, a twenty-eighth embodiment according to the present invention willbe explained below. This embodiment is a liquid crystal displayapparatus according to the twenty-fourth and twenty-sixth embodiments,in which: four common electrode potentials are employed; a firstpotential is a common electrode potential of a period when the scanningsignal driving circuit 202 scans the scanning electrodes 212 in order totransmit the video signal of one of the polarities of the video signalsto be inverted; a second potential is a potential of the pulse heightportion when the potential of the common electrodes 215 is changed intoa pulse shape after the first potential; a third potential is apotential after the completion of the pulse where the potential of thecommon electrodes 215 is changed into a pulse shape after the secondpotential and, at the same time, is a common electrode potential of aperiod when the scanning signal driving circuit 202 scans the scanningelectrodes 212 in order to transmit the video signal of the otherpolarity of the video signals to be inverted; and a fourth potential isa potential of the pulse height portion when the potential of the commonelectrodes 215 is changed into a pulse shape after the third potential.

An example of the waveforms according to the twenty-eighth embodiment issimilar to FIG. 28.

Next, a twenty-ninth embodiment according to the present invention willbe explained below. This embodiment is a driving method for a displayapparatus according to the twenty-fifth and twenty-seventh embodiments,in which: six common electrode potentials are employed; a firstpotential is a common electrode potential of a period when the scanningsignal driving circuit 202 scans the scanning electrodes 212 in order totransmit the video signal of one of the polarities of the video signalsto be inverted; a second potential is a potential of the pulse heightportion when the potential of the common electrodes 215 is changed intoa pulse shape after the first potential; a third potential is apotential after the completion of the pulse where the potential of thecommon electrodes 215 is changed into a pulse shape after the secondpotential; a fourth potential is a common electrode potential of aperiod when the scanning signal driving circuit 202 scans the scanningelectrodes 212 in order to transmit the video signal of the otherpolarity of the video signals to be inverted; a fifth potential is apotential of the pulse height portion when the potential of the commonelectrodes 215 is changed into a pulse shape after the fourth potential;and a sixth potential is a potential after the completion of the pulsewhere the potential of the common electrodes 215 is changed into a pulseshape after the fifth potential.

An example of the waveforms according to the twenty-ninth embodiment issimilar to FIG. 29.

Next, a thirtieth embodiment according to the present invention will beexplained below. This embodiment is a liquid crystal display apparatusaccording to the first through twenty-ninth embodiments described above,comprising: an irradiating unit 252 for irradiating the display unit 200with light as shown in FIG. 30; and a synchronizing circuit 251 formodulating the light intensity of the light irradiating unit 252 insynchronization with the video signal at a predetermined phase.

Further, this embodiment may be an apparatus according to the firstthrough twenty-ninth embodiments described above, comprising: a lightirradiating unit 254 for irradiating the display unit 200 with light asshown in FIG. 31; and a synchronizing circuit 253 for changing the colorof the light of the light irradiating unit 254 in synchronization withthe video signal at a predetermined phase.

Further, this embodiment may be an apparatus according to the firstthrough twenty-ninth embodiments described above, comprising: a lightirradiating unit 256 for irradiating the display unit 200 with light asshown in FIG. 32; and a synchronizing circuit 255 for modulating thelight intensity of the light irradiating unit in synchronization withthe video signal at a predetermined phase and, at the same time,changing the color of the light of the light irradiating unit 256 insynchronization with the video signal at a predetermined phase.

The light irradiating unit according to this embodiment may employ asurface emitting light source, or alternatively a backlight composed ofa light guide plate, a light source, and others optical elements.Alternatively, scanning may be performed by a beam-shaped or line-shapedlight source of a laser or the like.

The modulation of the light intensity may be performed by intensitymodulation or flashing of the light source itself, or by using amodulation filter capable of modulating the transmittance orreflectance.

Next, a thirty-first embodiment according to the present invention willbe explained below. This embodiment is a driving method for a displayunit according to the thirtieth embodiment, in which when division intoeach field or a plurality of colors is performed, the timing that thelight intensity of the light irradiating unit is modulated or that thecolor of light is changed is located at the time of completion of eachsubfield corresponding to the color, that is, immediately before thewriting of the video signals of the next field.

The operation of the thirty-first embodiment will be explained below.Since modulation of the light intensity or changing of the color oflight is performed in a fixed period at the time of completion of eachsubfield, light is projected in a state that the response of the displaysubstance of the display unit is relatively stable. This improvesefficiency in the light utilization, stabilizes display, and permitshigh definition display. Since the light intensity is modulated, thebrightness over the entire screen or in each of the regions divided intoa plurality of the regions can be adjusted, for example, in accordancewith the contents of video data. Specifically, when the majority of thecontents of video data is at dark gradation levels, the light intensityis reduced, while when the majority of the contents of video data is atlight gradation levels, the light intensity is increased, so that thefeeling of dynamics in image representation can be improved. Further, ina case that abnormalities such as flicker arise in the brightness, whenthe light intensity is modulated in response to the brightnessabnormalities, the abnormalities such as flicker in the brightness canbe suppressed.

Next, a thirty-second embodiment according to the present invention willbe explained below. This is an embodiment according to the first throughthirty-first embodiments described above, in which the potential of thevideo signals is determined by comparing: hold data of each pixel beforethe writing of the video signals; fluctuation in the pixel electrodepotential associated with the change in the potential of the commonelectrodes 215 changed into a pulse shape or the potential of thestorage capacitance electrodes 216 changed into a pulse shape or theboth potentials; and display data to be newly displayed.

Next, a thirty-third embodiment according to the present invention willbe explained below. This embodiment is a display apparatus according tothe thirty-second embodiment, in which the comparison between the dataand the fluctuation in the potential is performed by successivecomparison.

Further, in order to perform the successive comparison, this embodimentemploys: storing means for storing the original video signal data in thepreceding field or the video signal data including the correctionfinally applied in the preceding field; and comparison operation meansfor comparing the stored data with the video signal data to be newlydisplayed and thereby determining new signal data.

Next, a thirty-fourth embodiment according to the present invention willbe explained below. This is an embodiment according to thirty-secondembodiment, in which the comparison between the data and the fluctuationin the potential is performed using an LUT (look-up table orcorrespondence table) prepared in advance.

Further, in order to select necessary data from the correspondencetable, this embodiment employs: storing means for storing the originalvideo signal data in the preceding field or the video signal dataincluding the correction finally applied in the preceding field; andsearching means or addressing means for searching the stored data andthe video signal data to be newly displayed on the correspondence tableand thereby determining new signal data.

Next, the operation of the thirty-second through thirty-fourthembodiments of the invention is explained below. In a simple overdrivingmethod, as described in Patent Publication No. 3039506, when the imagedata of the preceding field is compared with the image data of the newfield and when the response of the display substance is taken intoconsideration, video signal data to be applied can basically bedetermined. On the other hand, in the invention, the common electrodepotential or the storage capacitance electrode potential or the both arechanged into a pulse shape. Thus, the effects of the change into a pulseshape need be taken into consideration. These effects are mainly apotential fluctuation caused by capacitance coupling and a temporarychange in the response time and the like caused by the potentialfluctuation. When the video signal in which these effects are taken intoconsideration is provided, the highest image quality is obtained in thedisplay according to the present invention. This video signal can begenerated by serial calculation, or alternatively by using a look-uptable prepared in advance.

Next, a thirty-fifth embodiment according to the present invention willbe explained below. This is an embodiment according to embodimentsemploying twisted nematic liquid crystal among the first throughthirty-fourth embodiments, in which the pulse shape change which is notreset is such that the mean tilt angle of the liquid crystal during thepulse shape change is 81 degrees or smaller. Preferably, the mean tiltangle of the liquid crystal is 65 degrees or smaller.

The operation of the thirty-fifth embodiment according to the presentinvention will be explained below. According to the comparison betweenexperiments, measurements, and computer simulations performed by thepresent inventors, the delay in the transition from a reset state in thetwisted nematic liquid crystal depends on the mean tilt angle of theliquid crystal. Further, the inventors have found that when the meantilt angle becomes 81 degrees or greater, a delay arises such that theorientation occurs in the direction opposite to the desired one.Further, when the mean tilt angle becomes 65 degrees or greater, thechange direction of the orientation temporarily becomes undetermined, sothat a delayed state arises. At the time of implementing the potentialfluctuation which is not reset, when the tilt angle is maintained belowthese mean tilt angles, good response characteristics without delay areachieved.

Next, a thirty-sixth embodiment according to the present invention willbe explained below. This embodiment is a display apparatus according tothe first through thirty-fifth embodiments described above, whichperforms display by integrated light digital driving in which the videosignal is used in the form of a digital signal while the potentialapplied to the display substance is a binary signal so that gradation isrepresented in the time axis direction.

The operation of the thirty-sixth embodiment will be explained below.Digital driving is performed in this embodiment. Such digital driving isdescribed, for example, in Patent Publication No. 3402602. The digitaldriving is described below with reference to FIG. 33 and FIG. 34. FIG.33 is a schematic diagram showing the waveforms in the prior art drivingmethod in which the potential of the common electrode is fixed while thepolarity of the video signal having an amplitude within a predeterminedrange relative to the common electrode potential is reversed within onesubfield period so that driving is performed and in the digital drivingmethod in which digital driving is performed using the same amplitude asthe maximum voltage amplitude of the video signal of the prior artdriving method. The common electrode potential to be fixed is shown by adash-dotted line, while the maximum potential and the minimum potentialof the video signal are shown by broken lines. In the prior art drivingshown in the upper part of FIG. 33, gradation is represented by themagnitude of the voltage value. That is, gradation is implemented bymodulation in the electric field strength. On the other hand, in thedigital driving shown in the lower part of FIG. 33, the voltage value isbinary, while the subfield period is divided into a plurality ofperiods, so that gradation is represented in a digital manner by thenumber of times of turning ON and OFF the voltage or the like. That is,gradation is implemented by the number of pulses. In the digital drivingshown in the lower part, the amplitude of the video signal voltage canbe twice the amplitude of the prior art. This permits remarkably rapidON-time response. Nevertheless, a delay similar to the delay in thetransition from a reset state can be generated in some cases. Further,the video signal cannot be reversed, and hence electric neutralitycannot be maintained in the display substance.

FIG. 34 is a schematic diagram showing the waveforms in the prior artdriving method in which the potential of the common electrode isreversed within one subfield period while the polarity of the videosignal having an amplitude within a predetermined range relative to thecommon electrode potential is reversed within one subfield period sothat driving is performed and in the digital driving method in whichdigital driving is performed using the same amplitude as the maximumvoltage amplitude of the video signal of the prior art driving method.The common electrode potential to be reversed is shown by a dash-dottedline, while the maximum potential and the minimum potential of the videosignal are shown by broken lines. In the prior art driving shown in theupper part of FIG. 34, gradation is represented by the magnitude of thevoltage value. That is, gradation is implemented by modulation in theelectric field strength. Further, the amplitude of the entire videosignal becomes approximately half that of FIG. 33. On the other hand, inthe digital driving shown in the lower part of FIG. 34, the voltagevalue is binary, while the subfield period is divided into a pluralityof periods, so that gradation is represented in a digital manner by thenumber of times of turning ON and OFF the voltage or the like. That is,gradation is implemented by the number of pulses. In contrast to thedigital driving shown in the lower part of FIG. 33, in the digitaldriving shown in the lower part of FIG. 34, the amplitude of the videosignal voltage becomes the same as that in the prior art, and hence theON-time response is also in the same order. On the other hand, a delaysimilar to the delay in the transition from a reset state is seldomgenerated. Further, the video signal can be reversed, and hence electricneutrality can be maintained in the display substance.

Also in such digital driving, the speedup realized by the technique ofthe invention acts effectively. In particular, in a configuration wheresufficient ON-time response is not obtained as shown in FIG. 34, theinvention is remarkably effective. The display unit and other variouskinds of circuits of the invention may be formed on distinct substratesor alternatively on the same substrate. Further, a part of the circuitsmay be formed on the same substrate, while the other circuits may beformed on distinct substrates.

The pixel electrodes arranged in a matrix shape may be arranged in astripe shape, a delta shape, or a Bayer arrangement (a checker shape),or alternatively in a PenTile arrangement where effective resolution isincreased in comparison with ordinary arrangements. The PenTilearrangement has been proposed by Clairvoyante laboratories. An exampleof this arrangement is shown in FIG. 35.

Next, a thirty-seventh embodiment according to the present inventionwill be explained below. This is an embodiment according to eachembodiment employing the field sequential display of the invention, inwhich the comparison between the data and the potential fluctuation isperformed using an LUT (look-up table or correspondence table) preparedin advance, depending on the polarity of the video signal relative tothe common electrode and the kind of color signal to be displayed.

In the thirty-eighth embodiment of the invention, an LUT (the look-uptable, correspondence table) is used that defines the correspondence ofa video signal with a gradation brightness obtained from the videosignal. Further, the LUT used differs depending on the polarity of thevideo signal and the kind of the color signal to be displayed.

Next, the operation of the thirty-seventh and thirty-eighth embodimentsof the invention is explained below. When an LUT is prepared incorrespondence to each color signal and the polarity of each videosignal, voltage application is performed in a manner optimal for eachcolor subfield, and hence display is performed in a manner optimal foreach color subfield. In the field sequential display, the optimalvoltage-transmittance characteristics depend on the color. Thus, when anLUT is prepared in correspondence to each color signal, thecharacteristics can be optimized for each color. Further, thefluctuation in the pixel potential slightly varies depending on thepolarity of the video signal. Thus, when an LUT is prepared incorrespondence to the polarity of each video signal, the characteristicscan be optimized for each polarity.

For simplicity, an LUT is prepared for converting the input video signaldata and the signal voltage outputted to the display unit depending oneach color signal and the polarity of each video signal as well as theorder of the change. In this method, the fluctuation in the potentialcannot be suppressed completely. However, the LUT can be generated bymeasuring, for each gradation, the relationship of the input videosignal data with the signal voltage outputted to the display unit when astill image is displayed on each display condition (such as a red imagewith positive polarity). Further, the size of the LUT is remarkablyreduced. The LUT used may be the same as the LUT used for adjusting theso-called voltage-transmittance curve and the gradation curve (y curve).FIG. 8 shows an example of a simple LUT for a red image. As shown inFIG. 8, the output voltage for the same video signal data is varieddepending on whether positive polarity or negative polarity.

Next, a thirty-ninth embodiment according to the present invention willbe explained below. This embodiment is a near-eye apparatus employingthe liquid crystal display apparatus according to the first throughthirty-eighth embodiments. Such near-eye apparatuses include: aviewfinder of a camera, a video camera, or the like; a head mountdisplay or a head-up display; and other apparatuses used in the vicinityof the eyes (for example, within 5 cm).

Since the thirty-ninth embodiment is applied to near-eye use, high imagequality is required such as good color reproduction, image clearness,and moving image sharpness. Accordingly, the invention provides a largeeffect.

Next, a fortieth embodiment according to the present invention will beexplained below. This embodiment is a projection apparatus employing theliquid crystal display apparatus according to the first throughthirty-eighth embodiments and thereby projecting an original image ofthe display apparatus through a projection optical system. Suchprojection apparatuses include: a projector such as a frontwardprojector and a rearward projector; and a magnifying observationapparatus.

Such a projection apparatus is used in projection application, and henceits image is expanded frequently at large magnification factors. Thus,high image quality is strictly required. Accordingly, the inventionprovides a large effect.

Next, a forty-first embodiment according to the present invention willbe explained below. This embodiment is a portable terminal employing theliquid crystal display apparatus according to the first throughthirty-eighth embodiments. Such portable terminals include a portabletelephone, an electronic notebook, a PDA (Personal Digital Assistance),and a wearable personal computer.

This portable terminal is used in an always carried application, andemploys a battery or a dry cell in many cases. Thus, low powerconsumption is required. Accordingly, the invention provides a largeeffect also in such an application. Further, the portable terminal isused indoors and outdoors in many cases. Thus, in order that sufficientluminosity should be obtained, the invention is satisfactorily appliedthat realizes a high efficiency in light utilization. Further, dependingon the carrying environment, the portable terminal is used in a widetemperature range. Thus, a large effect is obtained when the liquidcrystal display apparatus of the invention is employed that has a widetemperature range.

Next, a forty-second embodiment according to the present invention willbe explained below. This embodiment is a monitoring apparatus employingthe liquid crystal display apparatus according to the first throughthirty-eighth embodiments. Such monitoring apparatuses includemonitoring apparatuses for a personal computer, an AV (audio-visual)apparatus (such as a television receiver), medical applications, designuse, and viewing paintings.

This monitoring apparatus is used on a desk or the like for the purposeof detailed observation in many cases. Thus, high image quality isdesired, and hence the invention provides a large effect.

Next, a forty-third embodiment according to the present invention willbe explained below. This embodiment is a mobile display apparatusemploying the liquid crystal display apparatus according to the firstthrough thirty-eighth embodiments. Relevant transportation means includea car, an airplane, a ship, and a train.

The mobile display apparatus is not carried by a person as in theforty-first embodiment, and is attached to a transportation means. Thetransportation means suffers various environmental changes. Thus, theliquid crystal display apparatus of the invention is desirably employedthat hardly depends on environmental changes such as light intensity andtemperature as described above. Further, since a restriction is placedon the power supply, the liquid crystal display apparatus of theinvention is useful in that it has a low power consumption.

EXAMPLES

Next, effects will be explained below for examples of application of theliquid crystal display apparatus according to the embodiments of theinvention.

FIG. 46 is a sectional view showing the structure of a TFT array used inan example of the invention. With reference to FIG. 46, the unitstructure of a polycrystalline silicon TFT array is explained below inwhich amorphous silicon was modified into polycrystalline silicon.

A polycrystalline silicon TFT of FIG. 46 was fabricated by forming asilicon oxide film 28 on a glass substrate 29 and then growing amorphoussilicon. Next, annealing was performed using an excimer laser, so thatthe amorphous silicon was polycrystallized into a polycrystallinesilicon film 27. After that, a 10-nm silicon oxide film 28 was grown.After patterning, a photoresist was patterned in a size slightly largerthan the gate shape (for the purpose of forming LDD regions 23 and 24 ina subsequent process). Then, phosphorous ions were doped so that asource region (electrode) 26 and a drain region (electrode) 25 wereformed. After that, a silicon oxide film 28 used as a gate oxide filmwas grown. Then, amorphous silicon and tungsten silicide (WSi) servingas a gate electrode were grown. Then, a photoresist is patterned. Then,using the photoresist as a mask, the amorphous silicon and the tungstensilicide (WSi) were patterned into a gate electrode shape. Further,using the patterned photoresist as a mask phosphorous ions were dopedonly into necessary regions, so that LDD regions 23 and 24 were formed.After that, the silicon oxide film 28 and the silicon nitride film 21were grown continuously. Then, holes for contact were fabricated. Then,aluminum and titanium were formed by sputtering, and then patterned sothat a source electrode 26 and a drain electrode 25 were formed. Afterthat, a silicon nitride film 21 was formed over the entire surface.Then, holes for contact were fabricated. Then, an ITO film was formedover the entire surface, and then patterned so that a transparent pixelelectrode 22 was formed. As such, a planar type TFT pixel switch asshown in FIG. 46 was fabricated so that a TFT array was fabricated.Finally, a pixel array and a scanning circuit composed of TFT switcheswere obtained on the glass substrate.

In FIG. 46, a TFT was fabricated in which amorphous silicon waspolycrystallized. However, the TFT may be formed by growingpolycrystalline silicon and then improving the particle diameter of thepolycrystalline silicon by laser irradiation. Further, the laser may bea continuous wave (CW) laser in place of the excimer laser.

Further, when the process of polycrystallizing the amorphous silicon bylaser irradiation is omitted, an amorphous silicon TFT array can beformed.

FIG. 47( a) through FIG. 47( d) and FIG. 48( e) through FIG. 48( h) aresectional views showing a fabrication method for a polycrystallinesilicon TFT (planar structure) array, in the order of processes. Withreference to FIG. 47( a) through FIG. 47( d) and FIG. 48( e) throughFIG. 48( h), the fabrication method for a polycrystalline silicon TFTarray is explained below in detail. After a silicon oxide film 11 wasformed on a glass substrate 10, amorphous silicon 12 was grown. Next,annealing was performed using an excimer laser, so that the amorphoussilicon was polycrystallized (FIG. 47( a)). Then, a 10-nm thicknesssilicon oxide film 13 was grown. After patterning (FIG. 47( b)), aphotoresist 14 was applied and patterned (a p-channel region wasmasked). Then, phosphorous (P) ions were doped so that source and drainregions of the n-channel were formed (FIG. 47( c)). Then, after a 90-nmthickness silicon oxide film 15 serving as a gate insulating film wasgrown, amorphous silicon 16 and tungsten silicide (WSi) 17 serving as agate electrode were grown and then patterned into a gate shape (FIG. 47(d)).

A photoresist 18 was applied and patterned (an re-channel region wasmasked). Then, boron (B) was doped so that source and drain regions ofthe n-channel were formed (FIG. 48( e)). After the silicon oxide filmand the silicon nitride film 19 were grown continuously, holes forcontact were fabricated (FIG. 48( f)). Then, aluminum and titanium 20were formed by sputtering, and then patterned (FIG. 48( g)). As a resultof this patterning, formed are: source and drain electrodes of the CMOSof the peripheral circuit; data line wiring connected to the drain ofthe pixel switch TFT; and a contact to the pixel electrode. After that,a silicon nitride film 21 serving as an insulating film was formed.Then, holes for contact were fabricated. Next, an ITO (indium tin oxide)22 which was a transparent electrode serving as a pixel electrode wasformed and patterned (FIG. 48( h)).

As such, a TFT pixel switch of a planar structure was formed so that aTFT array was formed. The gate electrode was composed of tungstensilicide. However, another type of electrode such as a chromiumelectrode may be employed.

Liquid crystal was retained between the TFT array substrate fabricatedas described here and an opposing substrate provided with opposingelectrodes, so that a liquid crystal display panel was formed. Theopposing electrodes were fabricated by forming an ITO film over theentire surface of a glass substrate used as an opposing substrate, thenpatterning the film, and thereby forming a chromium patterning layer forlight shielding. The chromium patterning layer for light shielding maybe formed before the forming of the ITO film over the entire surface.Further, 2-μm columns were patterned on the opposing substrate. Thesecolumns were used as spacers for maintaining the cell gap and, at thesame time, provided with shock resistance. The height of the columns formaintaining the cell gap may be changed appropriately depending on thedesign of the liquid crystal panel. Orientation films were printed onthe mutually opposing surfaces of the TFT array substrate and theopposing substrate, and then rubbed with each other such that theorientation should be achieved at 90 degrees with each other afterassembling.

After that, sealant of ultraviolet curing was applied to the outside ofthe pixel region of the opposing substrate. Then, after the TFT arraysubstrate and the opposing substrate were opposed and bonded to eachother, liquid crystal was introduced so that a liquid crystal panel wasformed.

The chromium patterning layer serving as a light shielding film has beenprovided on the opposing substrate. However, the layer may be providedon the TFT array substrate. Further, obviously, the light shielding filmmay be composed of any kind of material other than chromium, as long asthe material can shield light. For example, WSi (tungsten silicide),aluminum, silver alloy, and the like may be used.

When the chromium patterning layer for light shielding is formed on theTFT array substrate, three kinds of structures are possible. In a firststructure, the chromium patterning layer for light shielding is formedon the glass substrate. After the forming of the patterning layer forlight shielding, the fabrication can be performed similarly to theabove-mentioned process. In a second structure, after a TFT arraysubstrate is fabricated into the above-mentioned structure, the chromiumpatterning layer for light shielding is finally fabricated. In a thirdstructure, in the middle of fabricating the above-mentioned structure,the chromium patterning layer for light shielding is fabricated. Whenthe chromium patterning layer for light shielding is formed on the TFTarray substrate, such a chromium patterning layer for light shieldingneed not be fabricated on the opposing substrate. Thus, the opposingsubstrate can be fabricated by forming an ITO film over the entiresurface and then patterning the film.

As described above, in an example of the invention, nematic liquidcrystal was retained between the above-mentioned TFT array substrate andthe opposing substrate, while orientation was achieved that was twistedat 90 degrees between both substrates and thereby implementing the TNmode. Further, a part of the scan electrode driving circuit, the signalelectrode driving circuit, and the synchronizing circuit, as well as apart of the common electrode potential control circuit, were fabricatedon the glass substrate.

A TFT panel fabricated as described above was used, while driving wasperformed in such a manner that overdrive was applied to the videosignal and that a pulse shape change was applied to the common electrodepotential. Further, liquid crystal having p/d=3 was used. Furthermore, acomparison operation circuit for video signal generation was alsoprovided. In this configuration, color field sequential driving wasperformed at 180 Hz. A backlight composed of an LED was used as a colortime-sharing light source.

The pixel pitch used was 17.5 μm, while display was performed at aresolution of VGA (horizontal 640 and vertical 480) within a displayhaving a diagonal length of 0.55 inches. Further, a buffer amplifiercomposed of a thin-film transistor was provided for a pixel at a cornerof the display area, so that fluctuation in the pixel potential wasmeasured. Further, a buffer amplifier for buffer amplifiercharacteristics measurement connected to the pixel electrode and havingbeen fabricated similarly was provided in the substrate. The values ofthe pixel potential described below are values obtained from themeasurement results of the buffer amplifier for buffer amplifiercharacteristics measurement and by correcting the output voltage bytaking the gain and the offset into consideration.

FIG. 36(A) through FIG. 36D show time-dependent behavior between thetransmittance and one of the common electrode potentials, the pixelelectrode potential, and the potential difference of the liquid crystallayer obtained from these potentials in this example. Here, in thepotential measurement, three kinds of gradation voltages for whiteimage, black image, and gray image (representing an intermediategradation state) were used. As seen from FIG. 36(A), the commonelectrode potential was changed similarly to FIG. 28. As seen from FIG.36(B), the pixel potential varies in response to writing of the videosignals. Further, also in a period without writing of the video signals,this value fluctuates in association with the response of the liquidcrystal. This is because even when the electric charge accumulatedbetween the pixel electrode and the common electrode is maintainedapproximately constant, the capacitance of the liquid crystal layervaries in association with the response of the liquid crystal, so that achange arises in the pixel potential. Further, when a pulse shape changeis started to be provided to the common electrode potential, the pixelpotential fluctuates remarkably owing to the capacitance coupling. FIG.36(C) shows the potential difference of the liquid crystal layercorresponding to the absolute value of the difference between the pixelelectrode potential and the common electrode potential. The pulse heightportion of the pulse shape change has a larger potential difference thanthe other period. This indicates that an overdrive-like effect isachieved. In the period of the pulse height portion, the fluctuation islarge in the pixel potential in association with the liquid crystalresponse. This suggests that the response of the liquid crystal isincreased so that a rapid change arises in the capacitance of the liquidcrystal layer. At the time of completion of the pulse shape change, thepixel potential fluctuates again owing to the capacitance coupling. FIG.36(D) shows the time-dependent change in the transmittance obtained fromthese waveforms. The transmittance is shown in an arbitrary unit. Whenthe video signal is written, the transmittance begins to vary. Then, ina period that the pulse shape change is provided, a rapid transmittancechange arises. After the completion of the pulse shape change, thetransmittance varies in a direction approaching a stable state of eachcondition.

Next, the characteristics of the display apparatus of an example of theinvention ware measured in the case that the environmental temperaturevaries. Further, the characteristics of this example ware compared witha comparative example of a 180-Hz color field sequential displayapparatus employing a method of a first publication (JapaneseTranslation of International Application (Kohyo) No. 2001-506376)adopting a combination of overdrive and reset driving. In order that theinfluence of temperature should be recognized accurately, in themeasurement, the display apparatus was installed in a thermostatic oven.Then, a temperature sensor adhered to the display unit was monitored,while the actual measurement was performed after 30 minutes had elapsedafter a desired temperature had been obtained, so that the display unitwas stably controlled into a desired temperature. FIG. 37 shows thesituation of time-dependent change of the transmittance in a white imagein an example of the invention when the temperature was changed between−10° C., 25° C., and 70° C. FIG. 38 shows the situation oftime-dependent change of the transmittance in a white image in acomparative example when the temperature was changed between −10° C.,25° C., and 70° C. In the example of the invention, after the pulseshape change is completed, the transmittance approaches a stable state,so that the transmittance reaches approximately the same value for everytemperature. In contrast, in the comparative example, at 70° C., thetransmittance rises rapidly after the reset, whereas the value risesonly gradually at 25° C. Further, at −10° C., the transmittance hardlyrises, and reaches only ⅕ or the like of the maximum achievabletransmittance reached at 70° C. FIG. 39 shows the comparison, between anexample of the invention and a comparative example, of the temperaturedependence of integrated light transmittance which is a value obtainedby integrating the transmittance over the period that the light sourceis turned ON in the color field sequential method. In actual usage, themean transmittance over the illumination period is more important thanthe maximum achievable transmittance. Here, the integrated lighttransmittance is used as the index. In the comparative example, a rapidchange arises in the integrated light transmittance in association withthe temperature change. At −10° C., the value is approximately 1/10 ofthat at 70° C. Thus, the apparatus of the comparative example cannot beused at low temperatures.

Further, the characteristics of the display apparatus of the inventionware measured in the case that the frequency of the color fieldsequential method is increased. Similarly to FIG. 37 through FIG. 39,the display apparatus employing the method of the first publication(Japanese Translation of International Application (Kohyo) No.2001-506376) was used in a comparative example. Used frequencies were180 Hz and 360 Hz, while the integrated light transmittance and thecontrast ratio were measured. Results are shown in FIG. 40. As seen fromFIG. 40, at 180 Hz, the integrated light transmittance and the contrastratio are approximately the same between the example and the comparativeexample. At 360 Hz, the comparative example shows a rapid decrease bothin the integrated light transmittance and in the contrast ratio. As aresult, the image was hardly recognized visually. In contrast, in theexample of the invention, at 360 Hz, the integrated light transmittancehas decreased to approximately 60% of the value of 180 Hz, whereas thecontrast ratio was almost unchanged. Thus, a good and visuallyrecognizable display was achieved, although slightly darker than that of180 Hz.

In the liquid crystal display apparatus of this example, a brightness of150 candela per square meter or greater was obtained. Thus, even undercomparatively intense outdoor daylight, the display could be visuallyrecognized well. Further, under extremely more intense light, thebacklight was turned OFF in response to a signal from an optical sensor,so that the apparatus could serve as a monochrome type displayapparatus.

As such, according to the present invention, in a transmission typetwisted nematic liquid crystal display apparatus, remarkably high-speedresponse is achieved that permits color field sequential driving at 360Hz.

Further, in the overdrive for a video signal according to the presentinvention, a lower voltage may be used than in the prior art overdrivingmethod. In this example, a voltage of 6V is applied in a black image asin the case of the pixel potential of FIG. 36(B). When normal driving isperformed for the liquid crystal material used here, since an appliedvoltage of 5V is necessary in a black image, the voltage in theoverdrive is 1V. On the other hand, in the prior art overdriving method,a voltage of 2-3V is applied in general. That is, 7-8V is necessary inthe prior art method for the material of this example, while 6V issufficient in the example. This difference arises from the fact that thespeedup is achieved effectively in the invention by means of the pulseshape change in the common electrode potential and the like which isequivalent to two-stage overdrive.

As described above, the invention is remarkably useful for the speedupof the response and the like of a liquid crystal display apparatus.

What is claimed is:
 1. A liquid crystal display apparatus comprising: aliquid crystal display unit; a video signal driving circuit; a scanningsignal driving circuit; a common electrode potential controllingcircuit; and a synchronizing circuit, wherein the display unit has ascanning electrode, a video signal electrode, a plurality of pixelelectrodes arranged in matrix form, a plurality of switching elementswhich transmit video signals to the pixel electrodes, and a commonelectrode, and wherein the common electrode potential controllingcircuit changes the potential of the common electrode into a pulse shapeafter the scanning signal driving circuit scans the entire scanningelectrodes and transmits video signals to the pixel electrodes, thepotentials of the video signals is determined by comparing the hold dataof the individual pixels before the writing of the video signals, avariation in the potentials of the pixel electrodes associated with avariation in the potentials of the common electrodes to be changed intoa pulse shape, the potentials of the storage capacitance electrodes tobe changed into a pulse shape, or the potentials of both of them, anddisplay data to be newly displayed, and, the comparison of the data andthe variation in the potentials is made by using LUTs (look-up tables,correspondence tables) prepared in advance, said LUTs differing from oneanother according to the polarity of the video signals.
 2. The liquidcrystal display apparatus according to claim 1, wherein said LUTsdiffers from one another according also to the colors of light beams ofthe light irradiating unit changed by synchronizing with the videosignals at the predetermined phase, in addition to the polarity of thevideo signals.
 3. The liquid crystal display apparatus according toclaim 1, wherein the potential of the common electrode changed into apulse shape is a potential which does not reset display on the liquidcrystal display unit.
 4. The liquid crystal display apparatus accordingto claim 1, wherein the potential of the common electrode varies betweenat least three potentials.
 5. The liquid crystal display apparatusaccording to claim 1 wherein the potential of the common electrode orthe storage capacitance electrode is changed into a pulse shape so as totemporarily increase a potential difference between the potential of thepixel electrode and the potential of the common electrode or the storagecapacitance electrode.
 6. The liquid crystal display apparatus accordingto claim 1 wherein the potential of the video signal is different fromthe potential of a video signal in a stable state during static drivingin consideration of the response characteristics of the display unitduring charge holding type driving.
 7. The liquid crystal displayapparatus according to claim 6 wherein the potential of the video signalis determined by taking into account the response characteristics of thedisplay unit and by comparing the hold data of individual pixels beforethe writing of the video signal and display data to be newly displayed.8. The liquid crystal display apparatus according to claim 1 wherein afield response type substance is sandwiched between the pixel electrodesand the common electrode of the display unit.
 9. The liquid crystaldisplay apparatus according to claim 8 wherein the field response typesubstance is made of a liquid crystal substance.
 10. The liquid crystaldisplay apparatus according to claim 9 wherein the liquid crystalsubstance is a nematic liquid crystal and has a twisted nematicalignment.
 11. The liquid crystal display apparatus according to claim10 wherein between the twist pitch p (μm) of the twisted nematicalignment of the liquid crystal substance and the average thickness d(μm) of the layer of the liquid crystal substance having the twistednematic alignment, a relationship p/d<20 is established.
 12. The liquidcrystal display apparatus according to claim 11 wherein between thetwist pitch p (μm) of the twisted nematic alignment of the liquidcrystal substance and the average thickness d (μm) of the layer of theliquid crystal substance having the twisted nematic alignment, arelationship p/d<8 is established.
 13. The liquid crystal displayapparatus according to claim 10 wherein the liquid crystal substancehaving the twisted nematic alignment is stabilized by a polymer having astructure almost continuously twisted.
 14. The liquid crystal displayapparatus according to claim 9 wherein the liquid crystal substance isin an electrically controlled birefringence mode.
 15. The liquid crystaldisplay apparatus according to claim 9 wherein the liquid crystalsubstance has a pie-type alignment (bend-type alignment).
 16. The liquidcrystal display apparatus according to claim 15 wherein an opticallycompensated plate is used in an OCB (optically compensatedbirefringence) mode.
 17. The liquid crystal display apparatus accordingto claim 9 wherein the liquid crystal substance is in a VA (verticalalignment) mode in which homeotropic alignment develops.
 18. The liquidcrystal display apparatus according to claim 17 wherein the liquidcrystal substance is provided with multidomains.
 19. The liquid crystaldisplay apparatus according to claim 9 wherein the liquid crystalsubstance is in an IPS (in-plane switching) mode in which the liquidcrystal substance responds by the action of an electric field which actsroughly parallel to a substrate surface.
 20. The liquid crystal displayapparatus according to claim 9 wherein the liquid crystal substance isin a FFS (fringe field switching) mode or an AFFS (advanced fringefield) mode.
 21. The liquid crystal display apparatus according to claim9 wherein the liquid crystal substance is a ferroelectric liquid crystalsubstance, an antiferroelectric liquid crystal substance, or a liquidcrystal substance exhibiting an electroclinic type response.
 22. Theliquid crystal display apparatus according to claim 9 wherein the liquidcrystal substance is a cholesteric liquid crystal substance.
 23. Theliquid crystal display apparatus according to claim 9 wherein the liquidcrystal substance is stabilized by a polymer having a structure in astate in which no voltage is applied or a low voltage is applied. 24.The liquid crystal display apparatus according to claim 1 wherein thedisplay unit is provided with a color filter to produce a color display.25. The liquid crystal display apparatus according to claim 1 wherein alenticular lens sheet, a lenticular film, or a double-sided prism sheetis provided to the display unit to produce a stereoscopic display. 26.The liquid crystal display apparatus according to claim 1 wherein acolor field sequential (color time-sharing) system is used in which avideo signal is divided into a plurality of color video signals whichcorrespond to a plurality of colors, light sources corresponding to theplurality of colors are synchronized with the plurality of color videosignals at a predetermined phase difference, and the plurality of colorvideo signals are displayed in time sequence.
 27. The liquid crystaldisplay apparatus according to claim 26 wherein a stereoscopic displaysystem of the color field sequential (color time-sharing) type is usedin which video signals consist of video signals for the right eye andvideo signals for the left eye, the video signals for one eye aredivided into a plurality of color video signals which correspond to aplurality of colors, light sources, which correspond to the colors andwhich are provided at two places, are synchronized with the videosignals for one eye at a predetermined phase difference and aresynchronized with the color video signal to display the video signalsfor one eye in time sequence, and at the same time, the video signalsfor one eye are displayed in time sequence as a plurality of color videosignals divided.
 28. The liquid crystal display apparatus according toclaim 1 wherein the pixel switch is an amorphous silicon thin filmtransistor display apparatus which is comprised of a thin filmtransistor of amorphous silicon.
 29. The liquid crystal displayapparatus according to claim 1 wherein the pixel switch is apolycrystalline silicon thin film transistor display apparatus which iscomprised of a thin film transistor of polycrystalline silicon.
 30. Theliquid crystal display apparatus according to claim 1 wherein the pixelswitch is comprised of a transistor of a single-crystalline silicon. 31.The liquid crystal display apparatus according to claim 1 wherein thepolarity of the video signals is reversed with a predetermined timing,and among the potentials of the common electrodes which varies between aplurality of potentials, one or two potentials whose application timeperiods are longer than those of the other potentials are approximatelyequal to an intermediate potential between the maximum potential and theminimum potential of all the potentials applied as the video signals.32. The liquid crystal display apparatus according to claim 1 whereinthe polarity of the video signals is reversed with a predeterminedtiming, and among the potentials of the common electrodes which variesbetween a plurality of potentials, one or two potentials whoseapplication time periods are longer than those of the other potentialsare approximately equal to either the maximum potential or the minimumpotential of the all the potentials which can be applied as the videosignals.
 33. The liquid crystal display apparatus according to claim 1wherein the common electrode potentials, which are provided immediatelybefore the scanning signal driving circuit starts to scan the scanningelectrode, are equal to the common electrode potentials producedimmediately after the scanning signal driving circuit scans the entirescanning electrodes and transmits video signals to the pixel electrodesand before the common electrode potentials are changed into a pulseshape.
 34. The liquid crystal display apparatus according to claim 1wherein the common electrode potentials, which are provided immediatelybefore the scanning signal driving circuit starts to scan the scanningelectrode, are different from the common electrode potentials producedimmediately after the scanning signal driving circuit scans the entirescanning electrodes and transmits video signals to the pixel electrodesand before the common electrode potentials are changed into a pulseshape.
 35. The liquid crystal display apparatus according to claim 34wherein the common electrode potentials, which are provided immediatelybefore the scanning signal driving circuit starts to scan the scanningelectrode, are approximately equal to one of a maximum voltage and aminimum voltage which can be produced as video signals to be applied andthe common electrode potentials, which are provided immediately afterthe scanning signal driving circuit scans the entire scanning electrodesand transmits video signals to the pixel electrodes and before thecommon electrode potentials are changed into a pulse shape, areapproximately equal to the other of the maximum voltage and the minimumvoltage which can be produced as video signals which have been applied.36. A driving method for a liquid crystal display apparatus wherein in adriving method for the liquid crystal display apparatus according toclaim 31, the common electrode potential varies to four potentials, thefirst potential being the common electrode potential provided at a timeperiod over which the scanning signal driving circuit scans the scanningelectrode to transmit video signals having one polarity of the videosignals reversed, the second potential being the potential of the pulseheight portion developed when the common electrode potential is changedinto a pulse shape following the provision of the first potential, thethird potential being a potential, which is developed after the commonelectrode potential is changed into a pulse shape following thedevelopment of the second potential, and the common electrode potentialat a time period over which the scanning signal driving circuit scansthe scanning electrode to transmit video signals having the otherpolarity of the video signals reversed, the fourth potential being thepotential of the pulse height portion formed when the common electrodepotential is changed into a pulse shape following the development of thethird potential.
 37. A driving method for a liquid crystal displayapparatus wherein in a driving method for the liquid crystal displayapparatus according to claim 32, the common electrode potential variesto six potentials, the first potential being the common electrodepotential provided at a time period over which the scanning signaldriving circuit scans the scanning electrode to transmit video signalshaving one polarity of the video signals reversed, the second potentialbeing the potential of the pulse height portion formed when the commonelectrode potential is changed into a pulse shape following theprovision of the first potential, the third potential being a potentialdeveloped after the common electrode potential is changed into a pulseshape following the development of the second potential, the fourthpotential is the common electrode potential developed at a time periodover which the scanning signal driving circuit scans the scanningelectrode to transmits video signals having the other polarity of thevideo signals reversed, the fifth potential being the potential of thepulse height portion formed when the common electrode potential ischanged into a pulse shape following the development of the fourthpotential, the sixth potential being a potential developed after thecommon electrode potential is changed into a pulse shape following thedevelopment of the fifth potential.
 38. The liquid crystal displayapparatus according to claim 1 having a light irradiating unit, whichirradiates the display unit with light, and a synchronizing circuitwhich synchronizes the intensity of light from the irradiating unit withthe video signals at a predetermined phase for modulation.
 39. Theliquid crystal display apparatus according to claim 1 having a lightirradiating unit, which irradiates the display unit with light, and asynchronizing circuit which synchronizes the colors of light from thelight irradiating unit with the video signals at a predetermined phaseto change the colors.
 40. The liquid crystal display apparatus accordingto claim 1 having a light irradiating unit, which irradiates the displayunit with light, and a synchronizing circuit which synchronizes theintensity of light from the light irradiating unit with the videosignals at a predetermined phase for modulation and which synchronizesthe colors of the light from the light irradiating unit with the videosignals at a predetermined phase to change the colors.
 41. The liquidcrystal display apparatus according to claim 38 wherein the lightintensity of the light irradiating unit is synchronized with the videosignals at a predetermined phase according to the polarity of the videosignals for modulation.
 42. A driving method for a liquid crystaldisplay apparatus wherein in a driving method for the liquid crystaldisplay apparatus according to claim 38, when the division intoindividual fields or a plurality of colors is conducted, the timing ofmodulating the light intensity of the light irradiating unit or ofchanging the color of the light is present during a fixed time periodafter the completion of subfield corresponding to the colors or a fixedtime period immediately before the writing of the video signals of thenext field.
 43. A driving method for a liquid crystal display apparatuswherein in a driving method for the liquid crystal display apparatusaccording to claim 39, when the division into individual fields or aplurality of colors is conducted, the timing of modulating the lightintensity of the light irradiating unit or of changing the color of thelight is present during a fixed time period after the completion ofsubfield corresponding to the colors or a fixed time period immediatelybefore the writing of the video signals of the next field.
 44. A drivingmethod for a liquid crystal display apparatus wherein in a drivingmethod for the liquid crystal display apparatus according to claim 40,when the division into individual fields or a plurality of colors isconducted, the timing of modulating the light intensity of the lightirradiating unit or of changing the color of the light is present duringa fixed time period after the completion of subfield corresponding tothe colors or a fixed time period immediately before the writing of thevideo signals of the next field.
 45. The liquid crystal displayapparatus according to claim 1 wherein the comparison of the data andthe variation in the potentials is made in order.
 46. The liquid crystaldisplay apparatus according to claim 2 wherein the LUTs (look-up tables,correspondence tables) describe a relationship between input video dataand output voltage to the display unit according to the order of thechange in the polarity of the video signals and the order of the changein the colors of light beams of the light irradiating unit.
 47. Theliquid crystal display apparatus according to claim 1, wherein in thechange into the pulse shape not to be reset of the liquid crystaldisplay apparatus using the twisted nematic liquid crystal, the meantilt angle of the liquid crystal during the change into the pulse shapeis 81° or less.
 48. The liquid crystal display apparatus according toclaim 47 wherein in the change into the pulse shape not to be reset, themean tilt angle of the liquid crystal during the change into the pulseshape is 65° or less.
 49. The liquid crystal display apparatus accordingto claim 1, wherein digital signals are used as the video signals,binary signals are used for the potentials applied to the displaysubstance, and the display is produced by using integrated light digitaldriving in which gradation is represented in a time-base direction. 50.A near-eye apparatus wherein the liquid crystal display apparatusaccording to claim 1 is used.
 51. A projection apparatus wherein theliquid crystal display apparatus according to claim 1 is used in aprojection apparatus which projects the base images of a displayapparatus by using a projection optical system.
 52. A portable terminalusing the liquid crystal display apparatus according to claim
 1. 53. Amonitoring apparatus using the liquid crystal display apparatusaccording to claim
 1. 54. A mobile display apparatus using the liquidcrystal display apparatus according to claim 1.